scholarly journals Modeling the Stress-Induced Transformation Behavior of Shape Memory Alloys under Multiaxial Loading Conditions

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1191
Author(s):  
Lei Chen ◽  
Hongying Zhang ◽  
Mitao Song ◽  
Xinxin Yue ◽  
Jian Zhang
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Yield Criterion ◽  
Plastic Behavior ◽  
Initial Surface ◽  
Transformation Behavior ◽  
Ductile Metals ◽  
Yield Criteria ◽  
Initial Transformation ◽  
Pseudoelastic Behavior

A large number of criteria to model the onset of plasticity for ductile metals have been proposed by researchers in the last century. Strangely, very few researchers have tried to model the stress-induced crystalline phase transformation of Shape Memory Alloys (SMAs) according to yield criteria. This paper focuses on the question: is a yield criterion originally proposed for describing the plastic behavior of metals suitable to model the “pseudoelastic” behavior of SMAs? To answer this question, two yield criteria originally proposed by the present author are used to predict the initial surface of transformation onset of two different SMAs: Cu-Al-Be and Ni-Ti alloy. The predicted initial transformation onset surfaces of the two SMAs are compared with experimental results and existing theories reported in the literature and some significant conclusions and recommendations are given.

scholarly journals Microstructure and Phase Transformation Analysis of Ni50−xTi50Lax Shape Memory Alloys

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 345 ◽  
Author(s):  
Weiya Li ◽  
Chunwang Zhao
Keyword(s):  
Phase Transformation ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Martensite Transformation ◽  
Transformation Behavior ◽  
Ni Content ◽  
Start Temperature

The microstructure and martensitic transformation behavior of Ni50−xTi50Lax (x = 0.1, 0.3, 0.5, 0.7) shape memory alloys were investigated experimentally. Results show that the microstructure of Ni50−xTi50Lax alloys consists of a near-equiatomic TiNi matrix, LaNi precipitates, and Ti2Ni precipitates. With increasing La content, the amounts of LaNi and Ti2Ni precipitates demonstrate an increasing tendency. The martensitic transformation start temperature increases gradually with increasing La content. The Ni content is mainly responsible for the change in martensite transformation behavior in Ni50−xTi50Lax alloys.

Cooling rate effects on the structure and transformation behavior of Cu-Zn-Al shape memory alloys

2014 ◽  
Vol 21 (11) ◽  
pp. 1109-1114 ◽  
Author(s):  
Nicoleta-Monica Lohan ◽  
Marius-Gabriel Suru ◽  
Bogdan Pricop ◽  
Leandru-Gheorghe Bujoreanu
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Cooling Rate ◽  
Transformation Behavior ◽  
Rate Effects

Experimental and FEM Analysis of the Fracture Behavior in NiTi Shape Memory Alloys

2006 ◽  
Vol 324-325 ◽  
pp. 919-922 ◽  
Author(s):  
Xin Mei Wang ◽  
Zhu Feng Yue
Keyword(s):  
Fracture Toughness ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Fracture Behavior ◽  
Micromechanical Model ◽  
Crack Tip ◽  
Fem Analysis ◽  
Transformation Behavior ◽  
Niti Shape Memory Alloys

In the present work, the fracture toughness of a NiTi pseudoelastic alloy has been obtained by experiments on CT specimens, which is KIC =39.38MPa·m1/2. Then the stress induced phase transformation behavior in front of the crack tip of the CT specimen is simulated by a micromechanical model considering the different elastic properties between martensite and austenite. The results show that the pre-crack promotes phase transformation at the crack tip. And the phase transformation is localised near the crack tip. It is also shown that phase transformation reduces the Mises stress around the crack tip.

Evolutions of Microstructure and Phase Transformation in Cu-Al-Fe-Nb/Ta High-Temperature Shape Memory Alloys

2015 ◽  
Vol 833 ◽  
pp. 67-70
Author(s):  
Shui Yuan Yang ◽  
Cui Ping Wang ◽  
Yu Su ◽  
Xing Jun Liu
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transformation Behavior ◽  
Two Phase ◽  
Phase Transformation Behavior ◽  
Three Phase

The evolutions of microstructure and phase transformation behavior of Cu-Al-Fe-Nb/Ta high-temperature shape memory alloys under the quenched and aged states were investigated in this study, including Cu-10wt.% Al-6wt.% Fe, Cu-10wt.% Al-4wt.% Fe-2wt.% Nb and Cu-10wt.% Al-4wt.% Fe-2wt.% Ta three types alloys. The obtained results show that after quenching, Cu-10wt.% Al-6wt.% Fe alloy exhibits two-phase microstructure of β′1 martensite + Fe (Al,Cu) phase; Cu-10wt.% Al-4wt.% Fe-2wt.% Nb alloy also has two-phase microstructure of (β′1 + γ′1 martensites) + Nb (Fe,Al,Cu)2 phase; Cu-10wt.% Al-4wt.% Fe-2wt.% Ta alloy is consisted of three-phase of (β′1 + γ′1 martensites) + Fe (Al,Cu,Ta) + Ta2(Al,Cu,Fe)3 phases. However, α (Cu) phase precipitates after aging for three alloys; and Fe (Al,Cu,Nb) phase is also present in Cu-10wt.% Al-4wt.% Fe-2wt.% Nb alloy. All the studied alloys exhibit complicated martensitic transformation behaviors resulted from the existence of two types martensites (β′1 and γ′1).

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