Deformation of Biomedical AuCuAl-Based Shape Memory Alloy Micropillars

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1411-1415 ◽  
Author(s):  
Akira Umise ◽  
Rui Serizawa ◽  
Sari Yanagida ◽  
Kenji Goto ◽  
Masaki Tahara ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Recovery ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Transformation Strain ◽  
Xrd Analysis ◽  
Second Phase ◽  
Shape Memory Property ◽  
Good Shape

ABSTRACTThe deformation behavior and shape recovery of an Fe-added AuCuAl shape memory alloy micropillar were investigated. XRD analysis revealed that Au-28Cu-22Al-2Fe (at.%) alloy contained a second phase which was evaluated to be α-Fe (bcc). SEM observation also confirmed the second phase at the surface of the micropillar specimen. A polycrystalline micropillar with 20 x 20 x 40μm rectangular was fabricated by a focused ion beam (FIB) system, and micro compress test was performed at room temperature. It was found that the yield stress of micropillar showed 50MPa, which must correspond to stress for inducing martensite. After the heating of the compressed micropillar, 1.75% shape recovery was recognized which is comparable to the transformation strain. Then, the Fe-added AuCuAl micropillar was concluded to possess good shape memory property, and thus this alloy may be suitable for small endovascular treatment which requires good X-ray radiography.

Pseudoelasticity of Cu-13.8Al-Ni Alloys Containing V and Nb

2008 ◽  
Vol 59 ◽  
pp. 101-107 ◽  
Author(s):  
Rodinei Medeiros Gomes ◽  
Ana Cris R. Veloso ◽  
V.T.L. Buono ◽  
Severino Jackson Guedes de Lima ◽  
Tadeu Antonio de Azevedo Melo
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Shape Recovery ◽  
Cold Water ◽  
Low Cost ◽  
Tensile Tests ◽  
Grain Refiner ◽  
Good Shape ◽  
Potential Applications ◽  
Superelastic Behavior

Polycrystalline copper-based shape memory alloys have been of particular interest in relation to Ni-Ti because of their low cost and good shape memory effect. Nevertheless the absence of a pronounced pseudoelasticity effect restricts the number of potential applications. In this work, the influence of Nb and V on the microstructure and the mechanical properties was investigated. Samples of Cu-13.8 Al-Ni containing V and Nb alloy were prepared by induction and solution treated at 850°C and then further quenched into cold water. The addition of Nb and V promotes the formation of precipitates which act as grain refiner and subsequently improve the mechanical properties. The tensile tests were performed at temperatures slightly inferior to Mf and superior to Af, to investigate the shape recovery and pseudoelasticity, respectively. Based on the analyses of the Cu-13,8Al-2Ni-1Nb (wt%) alloy was detected rupture strains greater than 14%, besides observation of the superelasticity of these alloys and quantification of this property by means of cycling, from 0 to strains between 1 and 7%. The studies performed on alloy Cu-13.8Al- 3,5Ni-1V (wt%) made it possible to determine rupture strains in the order of 3% and its superelastic behavior through cycling for deformations between 1 and 3%.

Plane Strain Sliding Contact Between a Rigid Cylinder and a Pseudoelastic Shape Memory Alloy Half-Space

2018 ◽  
Author(s):  
Ralston Fernandes ◽  
James G. Boyd ◽  
Dimitris C. Lagoudas ◽  
Sami El-Borgi
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Half Space ◽  
Maximum Stress ◽  
Transformation Strain ◽  
Elastic Half Space ◽  
Sliding Contact ◽  
Temperature Dependent ◽  
Rigid Cylinder ◽  
Parametric Studies

This study uses the finite element method to analyze the sliding contact behavior between a rigid cylinder and a shape memory alloy (SMA) semi-infinite half-space. An experimentally validated constitutive model is used to capture the pseudoelastic effect exhibited by these alloys. Parametric studies involving the maximum recoverable transformation strain and the transformation temperatures are performed to analyze the effects that these parameters have on the stress fields during indentation and sliding contact. It is shown that, depending on the amount of recoverable transformation strain possessed by the alloy, a reduction of almost 40 % of the maximum stress in the pseudoelastic half-space is achieved when compared to the maximum stress in a purely elastic half-space. The studies also reveal that the sliding response is strongly temperature dependent, with significant residual stress present in the half-space at temperatures below the austenitic finish temperature.

Characterization of Second-Phase Inclusion in Silicon Carbide Powders

2015 ◽  
Vol 821-823 ◽  
pp. 100-103
Author(s):  
Ta Ching Hsiao ◽  
Shen Tsao ◽  
Sergey Nagalyuk ◽  
Evgeny Mokhov
Keyword(s):  
Silicon Carbide ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Element Distribution ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Dual Beam ◽  
Metal Doped ◽  
Dopant Element

A specific transition metal is used as a dopant element in silicon carbide powders to create the compensation effect. According to ab-initio simulation, vanadium, chromium, and manganese-induced compensation decrease the lifetime of the acceptor carrier and cause higher resistance when boron is the main impurity. Since the silicon carbide lattice has low solubility, excess metal precipitates on the surface of powders, particularly on the grain boundaries. The compositions of matrix and precipitation in the powders reveal obvious differences between the two areas. The X-ray diffraction (XRD) pattern shows the structure of VSi2, which indicates the existence of a second phase. Dual-beam focused ion beam (DBFIB) is used to further analyze the geography inside the powders. A cross-section view by DBFIB shows a second phase in the grains with a composition similar to that in the grain boundary. Metal-doped silicon carbide powders are used as starting materials to conduct crystal growth with better dopant element distribution.

scholarly journals Xenon Focused Ion Beam in the Shape Memory Alloys Investigation - The Case of NiTi and CoNiAl

2014 ◽  
Vol 20 (S3) ◽  
pp. 334-335
Author(s):  
J. Kopeček ◽  
K. Jurek ◽  
V. Kopecký ◽  
L. Klimša ◽  
H. Seiner ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Focused Ion Beam ◽  
Ion Beam
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