A method of treating a shape memory alloy to improve its various characteristics and to cause it to exhibit a two-way shape memory effect. A raw shape memory alloy having a substantially uniformly fine-grained crystal structure is prepared and then its crystal orientations are arranged substantially in a direction suitable for an expected operational direction, such as tensile or twisting direction or the like, in which the shape memory alloy is expected to move when used in an actuator after the completion of the treatment.
TY - CONF. T1 - Computer simulation of microstructural evolution in Ni-rich TiNi shape memory alloys under applied stresses. AU - Li, D. Y.. AU - Chen, Long-qing. PY - 1998/1/1. Y1 - 1998/1/1. N2 - Coherent Ti11Ni14 precipitation in TiNi shape memory alloys and its variation under applied stresses were investigated using a diffuse-interface phase-field model. In this model, the structural difference between the precipitate phase and the matrix as well as the orientational difference between precipitate variants are distinguished by structural field variables, whereas the compositional difference between the precipitate phase and the matrix is distinguished by a concentration field variable. The temporal variation of the field variables is determined by solving the Ginzburg-Landau equations and the Cahn-Hilliard equation. Precipitate morphologies and their variation under strain-constraints were studied.. AB - Coherent Ti11Ni14 precipitation in TiNi shape memory alloys and its variation under ...
The application of Nitinol shape memory alloys (SMA) in steel connections is evaluated using connections incorporating SMA tendons. Shape memory alloys are a class of alloys that exhibit thermo-mechanical characteristics that are ideally suited for seismic applications. They have the ability to dissipate significant energy with little permanent deformation, and possess highly reliable energy dissipation based on a repeatable solid state phase transformation. To assess the validity of using SMA in real structures, two full-scale connections are tested. The tests are conducted on exterior joint specimens and tested according to the SAC testing protocol. The beams are W24 x 94 and the columns W14 x 159, all of A572 Grade 50 steel. Companion regular steel connections are tested for comparison. The connections are of a T-stub type, with four 11/2 inch diameter SMA rods providing the tensile resistance to the column. The specimens are re-tested several times to determine the ability of the SMA rods to ...
Define Magnesium alloy. Magnesium alloy synonyms, Magnesium alloy pronunciation, Magnesium alloy translation, English dictionary definition of Magnesium alloy. n. Symbol Mg A light, silvery-white, moderately hard metallic element that in ribbon or powder form burns with a brilliant white flame. Obtained chiefly...
Background: Restenosis following nitinol stent implantation in the superficial femoral artery (SFA) predominantly occurs within a year, but continues to occur with lower rates afterwards. However, factors associated with restenosis remain unclear. We sought to investigate the factors associated with restenosis within a year and beyond in this study.. Methods: We studied 431 limbs in consecutive 309 patients with peripheral artery disease (74±9 years, male 72%, claudicator 70%) who underwent successful endovascular therapy (EVT) for de novo SFA lesions. Nitinol stents (Luminexx in 93 limbs; Smart in 338 limbs) were provisionally deployed from April 2004 to December 2008. We classified the limbs as: early restenosis group = restenosis occurred within a year, 68 limbs; late restensosis group = restensosis occurred beyond a year, 24limbs; no-restenosis group, 339 limbs. Restenosis was detected by duplex ultrasound and stent fracture was identified by X-ray. A multiple logistic analysis was ...
Shape memory alloy (SMA) microactuators are under development for use in soft bodied robotics. These actuators take advantage of the shape memory effect of nickel-titanium alloys (nitinol) to deliver high force and large strain in a solid-state, thin film actuator. The actuators will be used for generating motion in an all-soft-material robotic platform that attempts to mimic some of the features of the tobacco hornworm caterpillar, Manduca Sexta. The devices described in this work are unique due to their thin patch-like structure, which will allow them to be laminated onto, or embedded into, the soft wall of the robot. The actuator patches consist of a nitinol microwire on a flexible polyimide base. The overall dimensions of the patches vary from 7.75 x 3.5 mm to 22 x 10 mm. The wires are 0.1 -0.8 mm wide. The polyimide is photodefined in a mesh structure so that the sheet is much more compliant in tension and compression than a flat sheet. The nitinol microwire meanders across the polyimide structure
TY - JOUR. T1 - Effect of travel speed on quality and welding efficiency of friction stir welded AZ31B magnesium alloy. AU - Baghdadi, Amir Hossein. AU - Selamat, Nor Fazilah Mohamad. AU - Sajuri, Zainuddin. AU - Kokabi, Amir Hossein. PY - 2018/1/1. Y1 - 2018/1/1. N2 - Weight reduction is one of the most concerning issues of automotive and aircraft industries in reducing fuel consumption. Magnesium (Mg) alloys are the lightest alloys which can be used in the structure due to low density and high strength to weight ratio. Developing a reliable joining process of magnesium alloys is required due to limited ductility and low workability at room temperature. Friction stir welding (FSW) is a solid-state welding process that can be performed to produce sound joints in magnesium alloys. Researchers have performed investigations on the effect of rotation and travel speeds in FSW of AZ31B magnesium alloy. However, there is lack of study on the FSW parameters, i.e. travel speed below 50 mm/min and ...
A shape memory alloy consists of a three element alloy of nickel-titanium-copper which is formed as being subjected to a cold working and to a heat treatment at a temperature below recrystallization point of the alloy for storing the shape, the alloy being thereby improved in operation stability and reliability even after repetitive operation and made wider in environmental temperature range for use therein of the alloy.
An implantable probe having an elongated sheath with provision for remotely positioning a device disposed within the elongated sheath. In one embodiment, the device is a circuit board, and a shape memory alloy (SMA) such as Nitinol is used to fabricate one or more actuators that are coupled to the circuit board. The shape memory effect exhibited by the SMA actuator is thermally activated. Electrical current is selectively applied to the actuator to resistively heat the SMA to a temperature sufficient to change its shape. When the shape of the SMA changes, the actuator moves the circuit board or other device longitudinally within the elongated sheath so that the light emitted is directed to a different portion of a treatment site. In another embodiment, the circuit board is rotated about its longitudinal axis within the sheath. In still another embodiment, the actuator moves a piston so as to pump a fluid through a pair of lumens disposed within the sheath to dissipate heat produced by the light emitting
We describe herein biocompatible single crystal Cu-based shape memory alloys (SMAs). In particular, we show biocompatibility based on MEM elution cell cytotoxicity, ISO intramuscular implant, and hemo-compatibility tests producing negative cytotoxic results. This biocompatibility may be attributed to the formation of a durable oxide surface layer analogous to the titanium oxide layer that inhibits body fluid reaction to titanium nickel alloys, and/or the non-existence of crystal domain boundaries may inhibit corrosive chemical attack. Methods for controlling the formation of the protective aluminum oxide layer are also described, as are devices including such biocompatible single crystal copper-based SMAs.
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A polycrystalline Ni 41Co 9Mn 40Sn 10 (at. %) magnetic shape memory alloy was prepared by arc melting and characterized mainly by magnetic measurements, in-situ high-energy X-ray diffraction (HEXRD), and mechanical testing. A large magnetoresistance of 53.8% (under 5 T) and a large magnetic entropy change of 31.9 J/(kg K) (under 5 T) were simultaneously achieved. Both of these values are among the highest values reported so far in Ni-Mn-Sn-based Heusler alloys. The large magnetic entropy change, closely related to the structural entropy change, is attributed to the large unit cell volume change across martensitic transformation as revealed by our in-situ HEXRD experiment. Furthermore, good compressive properties were also obtained. Lastly, the combination of large magnetoresistance, large magnetic entropy change, and good compressive properties, as well as low cost makes this alloy a promising candidate for multifunctional applications. ...
In this study some new concepts regarding certain aspects related to shape memory polymers are presented. A blend of polylactic acid (PLA) (80%) and polybutylene succinate (PBS) (20%) was prepared first by extrusion, then by injection molding to obtain the samples. Tensile, stress-relaxation and recovery tests were performed on these samples at 70 °C. The results indicated that the blend can only regain 24% of its initial shape. It was shown that, this partial shape memory effect could be improved by successive cycles of shape memory tests. After a fourth cycle, the blend is able to regain 82% of its shape. These original results indicated that a polymer without (or with partial) shape memory effect may be transformed into a shape memory polymer without any chemical modification. In this work, we have also shown the relationship between shape memory and property memory effect. Mono and multi-frequency DMA (dynamic mechanical analyzer) tests on virgin and 100% recovered samples of polyurethane (PU)
In spite of some good successes and excellent researches of Nickel-titanium shape memory alloy (NiTi-SMA) in reconstructive surgery, there are still serious limitations to the clinical applications of NiTi alloy today. The potential leakage of elements and ions could be toxic to cells, tissues and organs. This review discussed the properties, clinical applications, corrosion performance, biocompatibility, the possible preventive measures to improve corrosion resistance by surface/structure modifications and the long-term challenges of using SMAs.
With the progress of miniaturization, shape memory alloy (SMA) actuators exhibit high energy density, self-sensing ability and ease of fabrication, which make them well suited for practical applications. This paper presents a self-sensing controlled actuator drive that was designed using antagonistic pairs of SMA wires. Under a certain pre-strain and duty cycle, the stress between two wires becomes constant. Meanwhile, the strain to resistance curve can minimize the hysteresis gap between the heating and the cooling paths. The curves of both wires are then modeled by fitting polynomials such that the measured resistance can be used directly to determine the difference between the testing values and the target strain. The hysteresis model of strains to duty cycle difference has been used as compensation. Accurate control is demonstrated through step response and sinusoidal tracking. The experimental results show that, under a combination control program, the root-mean-square error can be reduced to 1.093
We have studied adiabatic temperature change Î"Tad in a Ni50Mn36Co1Sn13 metamagnetic shape memory alloy. An irreversible character of Î"Tad has been observed in the vicinity of the reverse martensitic transformation. In this region, cyclic application of the magnetic field converts comparatively large inverse magnetocaloric effect (MCE) with Î"Tadmax=-0.8 K to a weaker conventional MCE (Î"Tadmax=0.3 K). The crossover of Î"Tad has been attributed to the irreversible character of the magnetic field-induced transformation and the closeness of the martensitic transformation and Curie temperature of the austenitic phase TCA ...
small study in which 40 patients underwent nitinol stent placement in the SFA and then had a follow-up angiography, stent fracture occurred in 28% (11/40) after a mean follow-up of 13.6 months, more in patients who walked more in the time after the procedure. A retrospective analysis of 239 patients who underwent femoro-popliteal nitinol stent placement for claudication and critical limb ischemia reported a 4 year stent fracture rate of 17% and primary patency rate of 65%, similar to patients in whom there was no fracture. Clinical outcomes were not reported. A retrospective analysis of 742 limbs in 585 consecutive patients who underwent de novo SFA nitinol stent placement reported a primary and secondary patency rate of 67% and 86% at 6 years, respectively. Stent fracture, observed in 14% of limbs, was associated with early restenosis (P=0.0004). The association between stent fracture and clinical outcomes has been described in one small study of 53 patients who were followed for a median of 16 ...
Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magnetostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys (e.g., the martensitic transformation temperature T (M) ) sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C is a better predictor of the composition dependent T (M) than the number of valence electrons per atom (e/a) since the ...
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Cardiology Research and Practice is a peer-reviewed, Open Access journal that publishes original research articles, review articles, and clinical studies that focus on the diagnosis and treatment of cardiovascular disease. The journal welcomes submissions related to systemic hypertension, arrhythmia, congestive heart failure, valvular heart disease, vascular disease, congenital heart disease, and cardiomyopathy.
Cardiology Research and Practice is a peer-reviewed, Open Access journal that publishes original research articles, review articles, and clinical studies that focus on the diagnosis and treatment of cardiovascular disease. The journal welcomes submissions related to systemic hypertension, arrhythmia, congestive heart failure, valvular heart disease, vascular disease, congenital heart disease, and cardiomyopathy.
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We report the first-in-human experience with a new self-expanding THV and motorized delivery system. A TAVR with the CENTERA THV and motorized delivery system was performed successfully in 15 patients with good hemodynamic and clinical short- and midterm outcomes.. The CENTERA THV design shares some similarities with current balloon-expandable THVs (SAPIEN and SAPIEN XT, Edwards Lifesciences). All incorporate bovine pericardial tissue leaflets and an internal polyethylene terephthalate paravalvular seal and use relatively "short" stent frames. The salient difference is the self-expanding nitinol frame, with a flared inflow, narrower annular segment, and a larger-diameter outflow. This shape is designed to facilitate self-seating in the aortic annulus. In comparison with most other self-expanding nitinol valves the CENTERA THV does not extend into the ascending aorta for anchoring or self-alignment.. The CENTERA fixation and alignment is dependent on the self-seating stent frame but also on a ...
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0060] If Al or an alloy of Al and any one of Nd, Sc, C, Ni, B, Zr, Lu, Cu and Ag is used for the data wiring (62, 65, 66 and 67), the data wiring (62, 65, 66 and 67) may be formed as multiple layers including different types of layers formed on and/or under Al or the Al alloy. In an exemplary embodiment, the data wiring (62, 65, 66 and 67) is a double layer including any one of Mo(Mo alloy)/Al(Al alloy), Ti(Ti alloy)/Al(Al alloy), Ta(Ta alloy)/Al(Al alloy), Ni(Ni alloy)/Al(Al alloy) and Co(Co alloy)/Al(Al alloy) or a triple layer including any one of Ti(Ti alloy)/Al(Al alloy)/Ti(Ti alloy), Ta(Ta alloy)/Al(Al alloy)/Ta(Ta alloy), Ti(Ti alloy)/Al(Al alloy)/TiN, Ta(Ta alloy)/Al(Al alloy)/TaN, Ni(Ni alloy)/Al(Al alloy)/Ni(Ni alloy), Co(Co alloy)/Al(Al alloy)/Co(Co alloy) and Mo(Mo alloy)/Al(Al alloy)/Mo(Mo alloy). The alloy materials may include at least one element selected from the group consisting of Mo, W, Nb, Zr, V, O, and N ...
The creep mechanism of magnesium alloy at high temperature and the design methods of heat-resistant magnesium alloy system are introduced.The present research statue of heat-resistant magnesium alloy improved by the addition of rare earth(RE),alkaline(Ca,Sr)and other elements(Si、Bi、Sn) is reviewed.It is pointed out that the future direction of research and development of heat resistant magnesium alloy is to develop magnesium alloy with low cost,good castability and good comprehensive mechanical properties.
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Market analysis of how particular shape memory materials are likely to perform in the marketplace and how SMAs and SMPs are most likely to find their respective niches and price points. Shape memory materials are polymers or alloys that when deformed.
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The increasing use of aluminium alloys in high demand applications has lead to the development of a number of surface treatment technologies designed to improve hardness and wear characteristics. This thesis investigates the combination of a high power laser beam and an electric arc to produce new surfaces on aluminium alloys. Topics covered include: * The physics of the laser-arc-material surface interaction * Surface remelting of aluminium alloys * Surface alloying of aluminium alloys with Si, Fe and Ni * Arc stabilisation by laser irradiation * Optimisation of the laser-arc process parameters * Metallographic examination of the surfaces generated by laser-arc melting and analysis of the solidification rates. It was discovered that the addition of an arc source to the laser-material interaction lead to an improvement of surface properties and production rates.. ...
Self Expanding nitinol Stent indicated for use in the peripheral vasculature as well as for biliary stenting PROTEGE GPS The On-Target Stent Placement System The Protege™ GPS™ Self-Expanding Peripheral Stent is a self-expanding Nitinol stent system. The stent is made of a nickel titanium alloy (Nitinol) and comes on a 6F over-the-wire delivery system. The stent is cut from a Nitinol tube into an open lattice design and has tantalum radiopaque markers at the proximal and distal ends of the stent. Upon deployment, the stent achieves its predetermined diameter and exerts a constant, outward force to establish patency in the peripheral arteries. By Covidien - Medtronic ...
0039] The details of the invention and various embodiments can be better understood by referring to the figures of the drawing. Referring to FIG. 5, a graphical illustration of heat treatment profiles at 180 degrees C. is shown. The shape memory alloy material (a Ni--Ti shape memory alloy with a composition of about approximately 49.5 at. % Ni. and about approximately 50.5 at. % Ti) can be manufactured using metallurgical processes of melting, hot forging and rolling. Raw materials such as sponge Ti and Ni pellets can be melted at about approximately 1,300 to about approximately 1,600 degrees C. by melting in a furnace such as a high frequency vacuum induction melting furnace, arc melting furnace, or plasma melting furnace or the like. The material can be forged and rolled as appropriate. The material can then be formed into a primary product through cold working the material. Through cold working the shape and size of the material can be altered by plastic deformation or the increase of ...
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Shape memory polymers (SMPs) is a class of polymeric materials that are capable of changing shapes under an external stimulus such as heat, light, solvents and electromagnetic induction. In this dissertation, we explore both the bulk and surface shape memory effect of polymers, understand the material properties, and develop potential applications. In the first case (Chapter 2, Chapter 3, and Chapter 4), wrinkles were developed utilizing the surface SM effect and were applied for cell culture. Wrinkling has been generally understood as a stress-driven instability phenomenon. In our bilayer system, the wrinkle formation is enabled by compressive buckling of a gold coating that is first applied to an SMP that has been fixed with a temporary uniaxial strain. The bilayer system is then recovered thermally to generate the wrinkles. The fundamentals of wrinkle characteristics and formation were investigated in Chapter 2. Gold film thickness and applied prestrain of the SMP substrate show a direct impact on
We are very pleased to report the completion of enrolment in these two studies, as the results will add important clinical data around treatment for patients with peripheral arterial disease," said Mark A Turco, chief medical officer, Vascular Therapies, Covidien. "The results of the studies will enable physicians to make evidence-based decisions to allow for optimal patient outcomes. Covidien remains committed to bringing clinical data to the forefront, while working toward obtaining important disease and anatomic- specific labeling indications for our products.". VISIBILITY Iliac and DURABILITY Iliac study designs. VISIBILITY Iliac and DURABILITY Iliac are prospective studies being conducted at 23 centres in the USA and Europe. Of the 150 patients enrolled in the studies, 75 were treated with the Visi-Pro balloon expandable stent system in VISIBILITY Iliac, and 75 were treated with either the EverFlex self-expanding stent system or the Protégé GPS self-expanding nitinol stent and delivery ...
TiNiCu films were successfully prepared by co-sputtering of a TiNi target and a separate Cu target. Surface and cross-section microstructures of the deposited coating were analysed using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). Results showed that the deposited coating had fine grain size of about 300 to 400 nm and fully martensitic structure under room temperature. X-Ray Photoelectron Spectroscopy (XPS) indicated that there was an adherent and stable TiO2 oxide film on TiNiCu film surface, which can prevent Ni element from delamination. The deposited TiNiCu film has relatively strong (11 1) and (111) and relatively weak (010) texture. Results from Differential Scanning Calorimeter (DSC), in-situ X-Ray Diffraction (XRD) and curvature measurement revealed clearly martensitic transformation of the deposited TiNiCu films upon heating and cooling. Freestanding TiNiCu thin film showed clearly pronounced "two-way" shape memory ...
It is known that aluminum alloys can be classified as alloys for the production of castings and wrought alloys (rolling, extrusions, forgings and others). Wrought aluminum alloys are subdivided into heat-treatable alloys, those that respond to heat treatment to increase their mechanical strength and non heat-treatable alloys, whose mechanical properties can only be improved by cold working. The use of aluminum alloys has a great advantage due to the strength / weight ratio of Al, it has been used in industrial applications to different solutions, such as in the construction of automobiles, aerial and space vehicles, packaging and in overhead transmission lines. This paper aims to analyze the effect of heat treatment on the microhardness, ultimate tensile strength and in the elongation of the Al-0,18%Zr; Al-0.18%Zr-2.0%Mg and Al-0.18%Zr-6.0%Mg alloys compared to results obtained without heat treatment. The alloys were melted in a muffle furnace and cast in a water-cooled Cu mold. Samples were ...
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Increased requirements for crash energy management in automotive interiors have led to increased application of magnesium alloy AM50A. Successful integration of this new alloy with hot chamber diecasting process technology requires substantial adjustment and attention to processes and practices. This paper details the conversion of magnesium AZ91D steering column diecastings to high ductility structural alloy. Description is given of the changes made to foundry practices, casting parameters, process compliance monitoring, and hot end component management. The resulting improvements allow production of components comparable to the traditional alloy in manufacturing process demands while offering improved ductility and impact strength ...
A surgical snare having a wire which forms the snare loop made from a shape memory effect metallic alloy which exhibits superelasticity at room temperature. The wire is trained so that it assumes an intermediate snare loop size in an unrestrained free state. From this trained free state configuration, the loop can be expanded to a large loop and contracted to a very small loop without permanent deformation from the trained intermediate state. This range of movement enables an expanded range of applicability for snares in general, and also enables reducing the instrument tip size with improved loop configuration.
The U-Flex Stent is a peripheral self-expanding nitinol stent indicated for use in the iliac artery, superficial femoral artery (SFA) and proximal popliteal artery. It is availabe from 30 mm up to 200 mm length, using high flexible fine mesh design... additional information. ...
296001346 - EP 1015670 A1 2000-07-05 - COLOURING MAGNESIUM OR MAGNESIUM ALLOY ARTICLES - [origin: WO9842892A1] This invention provides a method for the anodisation of magnesium or magnesium based alloys using an electrolytic solution (preferably derived primarily from phosphoric acid) containing ammonia, amines or both. The use of such an aqueous electrolytic solution (irrespective of other additions) in at least preferred forms alters the conditions under which anodisation can occur to provide a more than satisfactory coating on the magnesium material with reduced cycle times.[origin: WO9842892A1] This invention provides a method for the anodisation of magnesium or magnesium based alloys using an electrolytic solution (preferably derived primarily from phosphoric acid) containing ammonia, amines or both. The use of such an aqueous electrolytic solution (irrespective of other additions) in at least preferred forms alters the conditions under which anodisation can occur to provide a more than
Acculink is the most extensively implanted* and studied* carotid stent, and is now the only system approved for both high risk and standard surgical risk patients. The self-expanding nitinol stent offers an open cell, nested ring design for conformability and flexibility with three longitudinal spins designed to minimize stent shortening ...
Table of Contents Chapter One Aluminium Alloy Industry Overview 1.1 Aluminium Alloy Definition 1.2 Aluminium Alloy Classification and Application 1.3 Aluminium…
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Figure 12: The duty cycle of the PWM can be changed and output on PORTB, although the period will remain the same.. A potentiometer allows us to easily adjust the duty cycle without having to manually enter code. The ADC on the Mega32 reads the voltage across the potentiometer, adjusting the duty cycle based on the ratio of the voltage to Vcc.. Matlab was used to log data during testing. The microcontroller connects to Matlab using the RS232 interface. A Matlab script reads data sent by the microcontroller and stores it into an array. The data can then be graphed and analyzed.. Results. Most of the results have been stated in the design sections. Most of the design changes made over the course of the project have been minor changes to accommodate unexpected problems, like the lateral joint movement. The biggest change that needs to be made is to the second joint. A new design is discussed in the conclusion section.. One of the major goals of the project has been completed; the nitinol joint does ...
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Alloy wheels are wheels that are made from an alloy of aluminium or magnesium. Alloys are mixtures of a metal and other elements. They generally provide greater strength over pure metals, which are usually much softer and more ductile. Alloys of aluminium or magnesium are typically lighter for the same strength, provide better heat conduction, and often produce improved cosmetic appearance over steel wheels. Although steel, the most common material used in wheel production, is an alloy of iron and carbon, the term "alloy wheel" is usually reserved for wheels made from nonferrous alloys. The earliest light-alloy wheels were made of magnesium alloys. Although they lost favor on common vehicles, they remained popular through the 1960s, albeit in very limited numbers. In the mid-to-late 1960s, aluminum-casting refinements allowed the manufacture of safer wheels that were not as brittle. Until this time, most aluminum wheels suffered from low ductility, usually ranging from 2-3% elongation. Because ...
Light Weight Metal Corrosion and Modeling: Thin, Nanoparticulate Coatings for the Improvement of the Corrosion and Passivation Behavior of AZ Magnesium Alloys
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Metal-induced artifacts in computed tomography and magnetic resonance imaging: comparison of a biodegradable magnesium alloy versus titanium and stainless steel ...
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tional 47: 66-69 (2012) [7] H. K., Lee, H. S., Han, K. J., Son, and S. B. Hong., Optimization of Nd-YAG laser welding parameters for sealing small titanium tube ends. J. of Materials Science and Engineering, Vol. A415, pp.149-155 (2006) [8] L. K., Pan, C. C., Wang, Y. C., Hsiso and K. C., Ho, Optimization of Nd-YAG laser wel-ding onto magnesium alloy via Taguchi analysis. J. of Optics & Laser Technology, Vol. 37, pp. 33-42 (2004) [9] Ibrahim, I. Z., et al., The effect of Gas Metal Arc Welding (GMAW) processes on different welding parameters. Procedia Engineering 41. ...
This specification covers a magnesium alloy in the form of sand castings.,p,These products have been used typically for parts operating in service up to 300 degrees F (149 degrees C) but usage is not limited to such applications.. ...
TM 1-1500-204-23-6 Table 4-7. Identification of Magnesium Alloys Commercial designation Current DOW1 ASTM2 AMC3 specification Conditions Sheet and Plate FSI AX31A C52S QQ-M-44 O (Fully Annealed) H24 (Strain Hardened Partially Annealed) H26 (Strain Hardened Partially Annealed) AX31B O (Fully Annealed) H24 (Strain Hardened Partially Annealed) Rods, Bars, and Shapes JI AZ61A C57S QQ-M-31 As Extruded FSI AZ31B C52S QQ-M-31 As Extruded M MIA 3S QQ-M-31 As Extruded 01 AZ80A C58S QQ-M-31 As Extruded Tubing FSI AX31 A C52S WW-T-825 JI AZ61A C57S WW-T-825 M MIA 3S WW-T-825 Commercial designation Current DOW ASTM AMC specification Type Temper Castings H A263A 265 QQ-M-56 Sand AC (As Cast) HT (Heat-Treated and Aged) ACS (As Cast and Stabilized) HTS (Heat-Treated and Stabilized) M MIB 403 QQ-M-56 Sand AC C A292A 260 QQ-M-56 Sand AC HT HTA ACS HTS A291 QQ-M-56 Sand AC HT HTA See footnotes at end of table. 4-15 ...
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The hot deformation simulation of a ZK60 magnesium alloy at different temperatures from 373 to 673 K and different strain rates of 0.1, 0.01 and 0.002 s−1was studied by using the Gleebe-1500...
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In many alloy systems, hydrogen embrittlement under relatively high fugacity conditions occurs by intergranular fracture. One of these is the iron nickel alloy system which exhibits intergranular hydrogen related fracture when tested with a high supersaturation of solute hydrogen or while being cathodically charged with hydrogen. The results obtained on this alloy system indicate that the hydrogen embrittlement susceptibility decreases as the iron concentration of the alloy increased. These early measurements contained no information about the grain boundary chemistry and it is known that the effects of hydrogen are generally sensitive to the concentrations of other elements at grain boundaries. One particular element, sulphur, is known to increase the susceptibility of nickel alloys and fe alloys to hydrogen embrittlement although the mechanism of this increased susceptibility is not known. (JES)*HYDROGEN EMBRITTLEMENT
The expansion and stability of foams made from remelted aluminium alloy scrap has been studied. Foams made from scrap alloy contain oxide bi-films introduced from the swarf (machining chips and turnings) of LM26 alloy and these oxides act as stabilizing agents. The wettability of the oxides and hence the stabilisation is studied by varying the addition of Mg (0 to 2 wt.%) in the alloy. The viscosity of the melts with and without Mg addition is measured and correlated with foam expansion and stability. A detailed microstructural analysis of the base alloy and foam cell wall was conducted to obtain an understanding of the stabilisation behaviour of oxides.. ...
Article Effect of accelerators and stabilisers on crystallinity of binary and ternary electroless nickel alloys. Autocatalytic binary and ternary Ni-P, Ni-W-P alloys films were prepared using alkaline citrate-based baths. The effect of succinic acid ...
Stent implantation has attracted significant attention since the urgent need of coronary angioplasty as the most common cause of heart attacks. Shape memory materials are able to have two shapes at different conditions. Since the smart materials are self-expandable, the presence of the balloon in stents eliminates due its problems like designing, material properties and dimension of balloons. In this study, we focused on shape memory polymers which have lots of advantages in comparison with shape memory alloys such as high elastic deformation, excellent processability, light weight, low cost, low density, and potential of biocompatibility so they have become a proper candidate for implant materials. It has been found that mechanical properties of polymeric materials can be improved by introducing a uniform dispersion of nanoparticles. The main goal of this paper is to describe the progressive self-expansion shape memory Polyurethane/Polycaprolactane-ZnO nano-composite blends. Fabrication of ...
Up to 40% lighter than some steel cylinders, Aluminum Alloy cylinders are made of high strength aluminum alloy with a corrosion resistant interior...
The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit ho
Aluminium Alloys 2006 - ICAA10: Solidification Structure and Casting Defect in a High-Speed Twin-Roll Cast A6022 Aluminium Alloy with Various Fe Contents
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AMS2355J revises fatigue testing methodology for 2XXX and 7XXX plate alloys, greater than 4 inches thick, updates referenced standards, and is a Five Year Review and update of this specification.. ...
Due to its unique characteristics, aluminum (Al) is used in a wide variety of commercial and industrial applications. Its utility can be further enhanced by combining it with other metals to create aluminum-based alloys, where the non-aluminum additives can make up to 15% of the total alloy, by weight. Because of its popularity and multiple compositions, the London Metal Exchange (LME) lists four different specifications for Al alloy compositions. In these specifications, silicon, copper, zinc, and iron are considered major additions, as they are mostly greater than 1% composition by weight. Therefore, these four elements must be determined with greater accuracy (± 2%) than the others. This work describes the determination of additives to Al in aluminum alloys at the LME specifications using the Avio® 200 hybrid scanning ICP-OES, an ideal choice for labs performing this application thanks to its charge-coupled device (CCD) detector, providing simultaneous background and analyte measurement, important
The World Market for Nickel and Nickel Alloy Tubes, Pipes, and Tube or Pipe Fittings - A 2009 Global Trade Perspective (Electronic book text) / Author: Inc. Icon Group International ; 9780546359053 ; Books
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TY - JOUR. T1 - Computer simulation of spinodal decomposition in Fe-Cr-Ni ternary alloys and Fe-Cr-Mo-Ni quaternary alloys. AU - Yang, Ling Ling. AU - Saito, Yoshiyuki. PY - 2012. Y1 - 2012. N2 - Numerical simulations of phase separation in Fe-Cr-Ni ternary alloys and Fe-Cr-Mo-Ni quaternary alloys similar to ferrite phases in duplex stainless steels were performed with using of the Cahn-Hilliard equations. A new numerical model based on the Gauss-Seidel and Newton-Raphson methods were utilized to obtain efficient and accurate solution. We obtained that small addition of Ni retard phase separation of Cr in Fe-Cr-Ni ternary alloys. The simulation results on behavior of Mo and Ni in Fe-Cr-Mo-Ni ternary alloys were quite similar to Mo in Fe-Cr- Mo and Ni in Fe-Cr-Ni ternary alloys. It is known that behavior of Mo or Ni along the trajectory of the peak tops of Cr concentration is determined by the sign of second derivative of Cr and Mo or which of Cr and Ni. The effect of Ni on the peak height of Cr ...
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New titanium alloys with improved biocompatibility have been developed for dental and biomedical applications. The osseointegration of implants depends on surface properties of these alloys; nature of the oxide film at the metal-oxide-bone. Also stress acted on the interface between bone and implant can occur the bone resorption due to stress shielding effects. So we have tried to improve this effect by manufacture of new ternary alloy containing Ta, Nb, and Zr alloying elements. The nanotube was formed mainly on -phase in case of Ti 30Ta-3Zr and Ti-30Nb-3Zr, but formed on -phase in case of Ti 30Ta-13Zr and Ti-30Nb-3Zr alloys. The polarization resistance of nanotube-formed new ternary alloy was lower than that of the non-nanotube formed alloy
Youre probably asking yourself "What is Shape Memory Alloy?" It sounds fancy and futuristic, but has actually been around in one way or another for decades. Very simply put, it is a metal alloy that can be deformed via heat, and return to its original form once it cools down. So how will GM apply this to engines?. The idea is to run exhaust gasses through different loops of SMA, turning an electric generator and thereby producing excess electricity. This surplus of power could then be used to augment an ICE engine with a hybrid drivetrain. As is already known, cars run purely on electric power tend to have their range cut short when certain accessories like air conditioning, heat, or flashing strobes are applied.. The idea of recycling waste heat to produce electric energy on an engine isnt a new idea either, and $2.7 million is a lot of ching to make a working prototype. Hopefully this isnt another pipe dream or dead end, though in theory the concept almost seems… sound? GM is partnering ...
The Department of Mechanical and Industrial Engineering Presents. Dr. Mohammad Elahinia. Associate Professor of Mechanical Engineering, University of Toledo. Topic: Additively Manufacturing NiTi Shape Memory and Superelastic Devices: A New Paradigm for Biomimetic Control. Abstract: Nickel-Titanium (NiTi) shape memory alloys (SMAs) with near-equiatomic exhibit both a thermal shape memory and superelasticity. Both effects are based on a reversible martensitic phase transformation. This type of the effect primarily depends on the transformation temperatures, which can be adjusted through variation in the Ni-Ti ratio. Currently, NiTi is the most commonly used SMA due to its outstanding functional characteristics and high working capacity, which far exceeds other SMAs. Due to the unique thermo-mechanical characteristic of these alloys, fabricating them to complex geometries has remained nearly impossible. Using additive manufacturing we have been able to achieve geometries and functionalities that ...
The most successful and best suited for rapid identification of alloys in field has been Handheld X-Ray Fluorescence (HHXRF). However, the XRF has inherent difficulty in analysis of many important aluminum alloys as well as other alloys containing low atomic number elements such as lithium, beryllium, boron, silicon or magnesium.
The final 3-year outcomes of the SUPERB trial showed that use of an interwoven nitinol stent design achieved high primary patency and maintained clinical durability outcomes in patients with lower-limb arterial obstructive disease. “Peripheral artery disease is a growing worldwide epidemic,” Lawrence A. Garcia, MD, from the division of cardiology and vascular medicine at St.
Lightweight construction in automobile and aircraft manufacture leads to a reduction in fuel consumption and carbon dioxide emissions. The utilisation of the magnesium alloys developed by Prof. Xiaoqin Zeng can make an effective contribution to these light construction endeavours. What is so innovative about the new alloy is that it contains rare earths as a special ingredient. Professor Dr. Karl Ulrich Kainer, head of the Geesthacht Magnesium Innovation Center at the Helmholtz Zentrum Geesthacht, explains the selection of this particular award winner as follows: "The possibilities of this new material family are highly promising. Professor Xiaoqin Zeng has presented groundbreaking results in the field of hardenable magnesium alloys for high-vacuum die casting processes ...
The creep characteristics of magnesium alloys and the ways to improve elevated temperature properties of magnesium alloys are summarized. The reasons of poor elevated temperature properties of the current Mg Al based alloys are analyzed. The current research and application status of the AZ?AS?AE?Mg Al Ca elevated temperature magnesium casting alloys are reviewed. The future research orientation is presented.
Shape memory alloys (SMA) are a class of ferroic materials which undergo a structural (martensitic) transition where the associated ferroic property is a lattice distortion (strain). The sensitiveness of the transition to the conjugated external field (stress), together with the latent heat of the transition, gives rise to giant mechanocaloric effects. In non-magnetic SMA, the lattice distortion is mostly described by a pure shear and the martensitic transition in this family of alloys is strongly affected by uniaxial stress, whereas it is basically insensitive to hydrostatic pressure. As a result, non-magnetic alloys exhibit giant elastocaloric effects but negligible barocaloric effects. By contrast, in a number of magnetic SMA, the lattice distortion at the martensitic transition involves a volume change in addition to the shear strain. Those alloys are affected by both uniaxial stress and hydrostatic pressure and they exhibit giant elastocaloric and barocaloric effects. The paper aims at ...
Dr Wei Min Huang is currently an Associate Professor at the School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore. He has 17 years of experience on shape memory materials (alloy, polymer, composite and hybrid) and technologies. He has published two books (Thin Film Shape Memory Alloys [co-ed., Cambridge University Press, 2009]; Polyurethane Shape Memory Polymer [co-au., CRC, 2011]) and over 100 papers in journals, such as Materials Today, Soft Matter, Journal of Materials Chemistry etc, and has been invited to review manuscripts from over 60 international journals and proposals from American Chemical Society etc. He is currently on the editorial board of four journals ...
A self-expanding, tapered profile stent for implantation in a body lumen, such as an artery, is disclosed. The stent is constructed of a plurality of radially expandable cylindrical elements generally aligned on a common longitudinal stent axis and interconnected by one or more interconnecting members placed so that the stent is flexible in the longitudinal direction. The lengths of the cylindrical elements increase from one end of the stent to the opposite end by increasing the lengths of the struts and the lengths of the interconnecting members. Each cylindrical element is formed from repeating patterns of upright Vs and inverted Vs connected by straight strut arms with shoulders to create an overall serpentine wave pattern around the circumference. A step, continuous, parabolic, or curved taper in the stent can be imparted by using an expansion mandrel and applying deforming forces to the stent. The stent is made from pseudoelastic and shape memory alloys.
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For oxide nanoparticles present in three oxide-dispersion-strengthened (ODS) Fe-12Cr-5Al alloys containing additions of (1) Y 2O 3 (125Y), (2) Y 2O 3 + ZrO 2 (125YZ), and (3) Y 2O 3 + HfO 2 (125YH), were investigated using transmission and scanning transmission electron microscopy. Furthermore, in all three alloys nano-sized (,3.5 nm) oxide particles distributed uniformly throughout the microstructure were characterized using advanced electron microscopy techniques. In the 125Y alloy, mainly Al 2O 3 and yttrium-aluminum garnet (YAG) phases (Y 3Al 5O 12) were present, while in the 125YZ alloy, additional Zr(C,N) precipitates were identified. The 125YH alloy had the most complex precipitation sequence whereby in addition to the YAG and Al 2O 3 phases, Hf(C,N), Y 2Hf 2O 7, and HfO 2 precipitates were also found. The presence of HfO 2 was mainly due to the incomplete incorporation of HfO 2 powder during mechanical alloying of the 125YH alloy. The alloy having the highest total number density of the ...
In this presentation, common die casting alloys are described and specific uses of each alloy in automotive applications are given. Some comparison of tensile and creep properties is included ...
The low density and high specific strength of magnesium alloys have created a great deal of interest in the use of these alloys in the automotive and aerospace industries and in portable electronics. All of these industries deal with applications in which weight is extremely important. However, an obstacle to overcome when using magnesium alloys in engineering applications are their unsatisfactory corrosion properties. This thesis is devoted to the atmospheric corrosion of the two magnesium alloys AZ91D and AM50, in particular the ways the microstructure and exposure parameters of these alloys influence their corrosion behaviour. The work includes both laboratory and field studies. The results obtained show that the microstructure is of vital importance for the corrosion behaviour under atmospheric conditions.. The microstructure of magnesium-aluminium alloys contains different intermetallic phases, e.g. Al8Mn5 and β-Mg17Al12. The local nobility of these intermetallic phases was measured on a ...
This report covers the present scenario and the growth prospects of the Global Metal Working Fluids market for the period 2014-2018. To arrive at a ranking of the leading vendors of the market, and to calculate the market size, the report considers the revenue generated through the sales of metal working fluids. It also presents the vendor landscape and a corresponding detailed analysis of the top four vendors in the Global Metal Working Fluids market. The report also provides data on the different segments of the Global Metal Working Fluids market, which are based on the following ...
E1834-18 Standard Test Method for Analysis of Nickel Alloys by Graphite Furnace Atomic Absorption Spectrometry lead content~ graphite furnace atomic absorption spectrometry~
Sliding friction experiments were conducted with various iron-base alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a single-crystal silicon carbide (0001) surface in vacuum. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is as an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.. ...
We report the case of a rare complication after coronary artery bypass graft (CABG) with non-traumatic fracture of nitinol thermoreactive sternal clips resulting a postoperative partial sternal dehiscence. A 61-year-old female patient administered to our department with severe coronary stenosis by coronary angiography and stabil angina pectoris symptoms. Physical examination were within normal limits. The electrocardiogram showed a normal sinus rhythm for 75/min. Arterial blood pressure was 130/90 mmHg. Lungs and heart were clear to auscultation. Patient was diagnosed with diabetes mellitus (DM) for several years with insulin treatment. She was obese with body mass index (BMI) 36.8 kg/m2. Rest of the physical and clinical evaluation was within normal limits. After preoperative preperation, patient underwent to three vessel CABG with conventional cardiopulmonary bypass. Due to intraoperative findings of obvious sternal osteoporosis and co-morbidities such as DM and higher BMI we applied 3 nitinol ...
A Guglielmi detachable coil (GDC) is a medical device made of platinum used in the treatment of brain aneurysms. It led to a revolutionary advance in the field of endovascular minimally-invasive surgery for the occlusion of cerebral vascular disease. Invented by Dr. Guido Guglielmi, Italian neurosurgeon and professor of UCLA interventional neuroradiology in 1990, and gradually introduced in the later 1990s as an alternative to invasive surgical clipping. In September 1995, the Guglielmi Detachable Coil (GDC) system received formal approval from the U.S. Food and Drug Administration (FDA) for treatment of surgically high-risk intracranial aneurysms. Due to advances and patent rights, not all coils used today are GDCs, however they are modeled on the same mechanism. These coils have special physical and electrolytic properties: the material is a high shape-memory alloy, allowing it to easily bend and regain its original coil shape. These platinum coils are fairly soft and adaptable to the shape ...
Metallic aluminum alloy foils exposed oil the forward, comet-facing surface of the aerogel tray oil the Stardust spacecraft are likely to have been impacted by the same cometary particle Population as the dedicated impact sensors and the aerogel collector. The ability of soft aluminum alloy to record hypervelocity impacts as bowl-shaped craters offers all opportunistic substrate for recognition of impacts by particles of a potentially wide size range. In contrast to impact surveys conducted oil samples from low Earth orbit, the simple encounter geometry for Stardust and Wild-2, with a known and constant spacecraft-particle relative velocity and effective surface-perpendicular impact trajectories, permits closely comparable simulation in laboratory experiments. For a detailed calibration program, we have selected a suite of spherical glass projectiles of uniform density and hardness characteristics, with well-documented particle size range from 10 mu m to nearly 100 mu m. Light gas gun buckshot ...
Currently, aortic valve replacement procedures require a sternotomy and use of cardiopulmonary bypass (CPB) to arrest the heart and provide a bloodless field in which to operate. A less invasive alternative to open heart surgery is transapical or transcatheter aortic valve replacement (TAVR), already emerging as a feasible treatment for patients with high surgical risk. The bioprosthetic valves are delivered via catheters using transarterial or transapical approaches and are implanted within diseased aortic valves. This paper reports the development of a new self-expanding stent for minimally invasive aortic valve replacement and its delivery device for the transapical approach under real-time magnetic resonance imaging (MRI) guidance. Made of nitinol, the new stent is designed to implant and embed a commercially available bioprosthetic aortic valve in aortic root. An MRI passive marker was affixed onto the stent and an MRI active marker to the delivery device. These capabilities were tested in ...
This was a multicenter retrospective case series of twelve hips (eleven patients) with adverse local tissue reactions secondary to corrosion at the modular neck-body junction. The cohort included eight women and three men who together had an average age of 60.1 years (range, forty-three to seventy-seven years); all hips were implanted with a titanium-alloy stem and cobalt-chromium-alloy neck. Patients presented with new-onset and increasing pain at a mean of 7.9 months (range, five to thirteen months) following total hip arthroplasty. After serum metal-ion studies and metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) revealed abnormal results, the patients underwent hip revision at a mean of 15.2 months (range, ten to twenty-three months). Tissue specimens were examined by a single histopathologist, and the retrieved implants were studied with use of light and scanning electron microscopy ...