Pseudoelastic stress-strain curves of polycrystalline shape memory alloys calculated from single crystal data

1989 ◽  
Vol 27 (3) ◽  
pp. 277-284 ◽  
Author(s):  
F. Falk
Keyword(s):  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Crystal Data ◽  
Stress Strain

THE USE OF SHAPE-MEMORY ALLOYS FOR MECHANICAL REFRIGERATION

2009 ◽  
Vol 02 (02) ◽  
pp. 73-78 ◽  
Author(s):  
LLUÍS MAÑOSA ◽  
ANTONI PLANES ◽  
EDUARD VIVES ◽  
ERELL BONNOT ◽  
RICARDO ROMERO
Keyword(s):  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Large Temperature ◽  
Martensitic Transition ◽  
Stress Strain ◽  
Temperature Changes ◽  
Entropy Changes ◽  
Elastocaloric Effect ◽  
Different Temperatures

This letter reports on stress–strain experiments on a Cu – Zn – Al single crystal performed using a purpose-built tensile device which enables the load applied to the specimen to be controlled while elongation is continuously monitored. From the measured isothermal tensile curves, the stress-induced entropy changes are obtained at different temperatures. These data quantify the elastocaloric effect associated with the martensitic transition in shape-memory alloys. The large temperature changes estimated for this effect, suggest the possibility of using shape-memory alloys as mechanical refrigerators.

A phenomenological model for thermally-induced hysteresis in polycrystalline shape memory alloys with internal loops

2021 ◽  
pp. 1045389X2110482
Author(s):  
Yuxiang Han ◽  
Haoyuan Du ◽  
Linxiang Wang ◽  
Roderick Melnik
Keyword(s):  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Phenomenological Model ◽  
Landau Theory ◽  
Thermally Induced ◽  
First Order ◽  
Proposed Model ◽  
Crystal Model ◽  
Hysteretic Response

In the current study, a 1-D phenomenological model is constructed to capture the temperature-induced hysteretic response in polycrystalline shape memory alloys (SMAs). The martensitic and austenitic transformations are regarded as the first-order transitions. A differential single-crystal model is formulated on the basis of Landau theory. It is assumed that the transformation temperatures follow the normal distribution among the grains due to the anisotropic stress field developed in the material. The polycrystalline hysteretic response is expressed as the integration of single-crystal responses. Besides, the prediction strategy for incomplete transitions is presented, and the first-order reversal curves are obtained via density reassignment. The proposed model is numerically implemented for validation. Comparisons between the modeling results and the experimental ones demonstrate the capability of the proposed model in addressing the hysteresis in thermally-induced phase transformations.

Micro pulling down growth of very thin shape memory alloys single crystals

2017 ◽  
Vol 10 (01) ◽  
pp. 1740003 ◽  
Author(s):  
I. López-Ferreño ◽  
J. San Juan ◽  
T. Breczewski ◽  
G. A. López ◽  
M. L. Nó
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Single Crystals ◽  
Functional Materials ◽  
Small Scale ◽  
Cylindrical Shape ◽  
Minimum Diameter ◽  
Wide Range

Shape memory alloys (SMAs) have attracted much attention in the last decades due to their thermo-mechanical properties such as superelasticity and shape memory effect. Among the different families of SMAs, Cu–Al–Ni alloys exhibit these properties in a wide range of temperatures including the temperature range of 100–200[Formula: see text]C, where there is a technological demand of these functional materials, and exhibit excellent behavior at small scale making them more competitive for applications in Micro Electro-Mechanical Systems (MEMS). However, polycrystalline alloys of Cu-based SMAs are very brittle so that they show their best thermo-mechanical properties in single-crystal state. Nowadays, conventional Bridgman and Czochralski methods are being applied to elaborate single-crystal rods up to a minimum diameter of 1[Formula: see text]mm, but no works have been reported for smaller diameters. With the aim of synthesizing very thin single-crystals, the Micro-Pulling Down ([Formula: see text]-PD) technique has been applied, for which the capillarity and surface tension between crucible and the melt play a critical role. The [Formula: see text]-PD method has been successfully applied to elaborate several cylindrical shape thin single-crystals down to 200[Formula: see text][Formula: see text]m in diameter. Finally, the martensitic transformation, which is responsible for the shape memory properties of these alloys, has been characterized for different single-crystals. The experimental results evidence the good quality of the grown single-crystals.

On the stress-assisted aging in NiTiHfPd single crystal shape memory alloys

2018 ◽  
Vol 725 ◽  
pp. 51-56 ◽  
Author(s):  
E. Acar ◽  
H. Tobe ◽  
H.E. Karaca ◽  
I. Chumlyakov
Keyword(s):  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Crystal Shape

A Phenomenological Description on Thermomechanical Behavior of Shape Memory Alloys

1990 ◽  
Vol 112 (2) ◽  
pp. 158-163 ◽  
Author(s):  
K. Tanaka
Keyword(s):  
Constitutive Equation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Thermomechanical Behavior ◽  
Heating Process ◽  
Recovery Stress ◽  
Transformation Kinetics ◽  
Stress Strain ◽  
Temperature Relation ◽  
Ni Alloy

A constitutive theory, which consists of the constitutive equation and the transformation kinetics, is proposed to describe the thermomechanical behaviors of the shape memory alloys. Simulation in Ti-Ni alloy proves a good applicability of the theory when the overall characteristics of the stress-strain-temperature relation and the recovery stress induced in the heating process are studied in the uniaxial state.

Phase quantification during pseudoelastic cycling of Cu–13.1Al–4.0Ni (wt.%) single-crystal shape memory alloys using neutron diffraction

2008 ◽  
Vol 56 (17) ◽  
pp. 4724-4738 ◽  
Author(s):  
Ganesh K. Kannarpady ◽  
Abhijit Bhattacharyya ◽  
Mike Wolverton ◽  
Donald W. Brown ◽  
Sven C. Vogel ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Shape Memory Alloys ◽  
Single Crystal ◽  
Shape Memory ◽  
Crystal Shape ◽  
Phase Quantification
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