EFFECT OF TRANSFORMATION VOLUME STRAIN ON THE SPHERICAL INDENTATION OF SHAPE MEMORY ALLOYS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5957-5964 ◽  
Author(s):  
WENYI YAN ◽  
QINGPING SUN ◽  
HONG-YUAN LIU
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Indentation Depth ◽  
Mechanical Response ◽  
Spherical Indentation ◽  
Indentation Hardness ◽  
Volume Strain ◽  
Volume Contraction ◽  
Indentation Force

The mechanical response of spherical indentation of superelastic shape memory alloys (SMAs) was theoretically studied in this paper. Firstly, the friction effect was examined. It was found that the friction influence is negligibly small. Secondly, the influence of the elasticity of the indenter was investigated. Numerical results indicate that this influence can not be neglected as long as the indentation depth is not very small. After that, this paper focused on the effect of transformation volume contraction. Our results show that the transformation volume contraction due to forward martensitic transformation can reduce the maximum indentation force and the spherical indentation hardness. These research results enhance our understanding of the spherical indentation responses, including the hardness of the smart material SMAs.

Spherical Indentation of Superelastic Shape Memory Alloys

2007 ◽  
Vol 334-335 ◽  
pp. 601-604
Author(s):  
Wen Yi Yan ◽  
Qing Ping Sun
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Bifurcation Point ◽  
Reverse Transformation ◽  
Spherical Indentation ◽  
Indentation Hardness ◽  
Characteristic Points ◽  
Forward Transformation ◽  
Transformation Stress ◽  
Return Point

Spherical indentation of superelastic shape memory alloys (SMAs) has been theoretically analyzed. Two characteristic points on the superelastic indentation curve have been discovered. The bifurcation force corresponding to the bifurcation point relies on the forward transformation stress and the return force corresponding to the return point relies on the reverse transformation stress. Based on these theoretical relationships, an approach to determine the transformation stresses of superelastic SMAs has been proposed. To improve the accuracy of the measurement, a slope method to locate the two characteristic points from the slope curves is further suggested. Additionally, the spherical indentation hardness was also analyzed.

Characterization of NiTi superelastic properties by nano-dynamic modulus analysis and nanoindentation

2017 ◽  
Vol 10 (02) ◽  
pp. 1650071 ◽  
Author(s):  
Meni Kabla ◽  
Doron Shilo
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Dynamic Modulus ◽  
Indentation Depth ◽  
Modulus Analysis ◽  
Reduced Modulus ◽  
Transformation Stress

Nano-dynamic modulus analysis (DMA) is a technique that allows measuring the reduced modulus during nanoindentation. This paper demonstrates the usefulness of nano-DMA in the characterization of superelastic properties of shape memory alloys. Measurements of reduced modulus as a function of the indentation depth reveal a transition, which is associated with the finish of the martensitic transformation at the region right beneath the tip. Further analysis of nanoindentation data at the transition indentation depth allows the evaluation of representative properties which are proportional to the transformation stress and the strain at the end of the martensitic transformation and can be used for comparing between different samples.

Spherical indentation for determining the phase transition properties of shape memory alloys

2009 ◽  
Vol 24 (3) ◽  
pp. 1082-1086 ◽  
Author(s):  
Linmao Qian ◽  
Shuang Zhang ◽  
Dongyang Li ◽  
Zhongrong Zhou
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Tensile Tests ◽  
Deformation Analysis ◽  
Spherical Indentation ◽  
Indentation Method ◽  
Indentation Force ◽  
Depth Curves

A spherical indentation method was developed to characterize the phase transition behaviors of shape memory alloys (SMAs). Based on deformation analysis, the measured indentation force-depth curves of SMAs can be converted to their nominal stress-strain curves. The predicted elastic modulus and phase transition stress of SMAs from spherical indentation agree well with those directly measured from tensile tests. This approach should be especially useful for characterizing the phase transition properties of SMA materials of small size or thin films.

scholarly journals Spherical indentation hardness of shape memory alloys

2006 ◽  
Vol 425 (1-2) ◽  
pp. 278-285 ◽  
Author(s):  
Wenyi Yan ◽  
Qingping Sun ◽  
Hong-Yuan Liu
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Spherical Indentation ◽  
Indentation Hardness

Atomic Order and Martensitic Transformation in Cu-Al-Be Shape Memory Alloys

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-973-C8-978
Author(s):  
M. Jurado ◽  
Ll. Mañosa ◽  
A. González-Comas ◽  
C. Stassis ◽  
A. Planes
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Atomic Order

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

Sign in / Sign up

Export Citation Format

Share Document