Effect of Aging Treatment on Transformation Temperature Difference and Temperature Hystelisis of Ti-Ni-Cu Shape Memory Alloy after Pre-Deforming

Cho, H.; Mutoh, Kenichiro; Takeda, Yoichi; Yamamoto, Takaei; Sakuma, Toshio

doi:10.14723/tmrsj.35.355

Cited by 5 publications

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Role of dislocations on martensitic transformation temperatures and microstructure: A molecular dynamics study

Farache,

Mishra,

Tripathi

et al. 2024

Journal of Applied Physics

View full text Add to dashboard Cite

Microstructure and defects strongly affect martensitic transformations in metallic alloys. Significant progress has been made in understanding the atomic-level processes that control the role of grain boundaries and precipitates in these solid-to-solid phase transformations. Yet, the role of dislocations and their structures on martensitic transformation temperature and the resulting microstructure remains unclear. Therefore, we used large-scale molecular dynamics simulations to study the forward and reverse transformation of a martensitic material modeled after Ni63Al37 under cyclic thermal loading. The simulations reveal that dislocations in the austenite phase act as one-dimensional seeds for the martensite phase, which is present at temperatures significantly above the martensite start value. We find a reduction in the dislocation density during cyclic thermal loading, which results in the increase in martensite and austenite transition temperatures, in agreement with experiments. Importantly, we extracted a critical martensitic nuclei size for developing stable domains and found that relatively low dislocation densities are needed to grow independent martensitic variants resulting in a multi-domain structure.

show abstract

Role of dislocations on martensitic transformation temperatures and microstructure: A molecular dynamics study

Farache,

Mishra,

Tripathi

et al. 2024

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

Effects of Ambient Temperature and Ni-content on Function Deterioration Process of Ti-Ni Shape Memory Alloy

Cho

Yamamoto

Sakuma

2011

Trans. Mat. Res. Soc. Japan

Self Cite

View full text Add to dashboard Cite

In order to improve the durability of performance of actuator using shape memory alloy, the effect of ambient temperature and Ni-content on function deterioration process of Ti-Ni shape memory alloy is investigated. The function deterioration process is investigated by repeated loading-unloading tests with constant strain condition. The chemical compositions of specimens are Ti-50.1 at%Ni, Ti-50.3 at%Ni and Ti-50.6 at%Ni and the cold working ratio is 43.0 %. Heat-treatment condition is at 673 K for 3.6 ks. The ambient temperature range is from 353 to 473 K. The decrement of recovery strain decreases with increasing of ambient temperature. It is caused by the increase of applied stress with increasing ambient temperature. However, when applied strain is about 2 %, the decrement of recovery strain hardly increases with increasing ambient temperature up to 433 K. From this result, when the applied stress is less than about 2 %, this sample can be used under a high temperature consecutively. Meanwhile, the increasing of Ni-content leads to the increasing of applied stress. However, the decrement of recovery strain decreases with increasing Ni-contents. This tendency is interpreted to be caused by the increase of precipitates (Ti 3 Ni 4) and decrease of grain size with increasing Ni-contents.

show abstract

Effect of Heat-treatment Time on Performance Recovery of Ti-50.4at%Ni Shape Memory Alloy

Cho

Yamamoto

Sakuma

2012

Trans. Mat. Res. Soc. Japan

Self Cite

View full text Add to dashboard Cite

In this research, the effect of heat treatment time on the performance recovery of Ti-Ni shape memory alloy (SMA) is investigated. The chemical composition of specimen is Ti-50.4 at%Ni, and cold working ratio is 30 %. At first, the specimen is heat-treated at 673 K for 3.6 ks. And then, the specimen is heat-treated for recovery of function after isothermal 1000 times loading-unloading test under constant strain. The heat-treatment temperature for performance recovery is 573 K, and heat-treatment time is varied from 0.6 to 3.6 ks. The functional deterioration process of specimens heat-treated for performance recovery is investigated by the isothermal loading-unloading tests under constant strain. Recovery strain and critical stress for inducing martensite increase with increasing heat-treatment time, and are saturated when heat-treatment time is more than 1.8 ks. Moreover, the number of cycle to failure increases with increasing heat-treatment time up to 1.8 ks, has a maximum at 1.8 ks, and then followed by a decrease. These tendencies are caused by a variation of the dislocation density owing to the variation of the heat-treatment condition. From these results, the optimal heat-treatment time for performance recovery is 1.8 ks when heat-treatment temperature is 573K.

show abstract

Effect of Aging Treatment on Transformation Temperature Difference and Temperature Hystelisis of Ti-Ni-Cu Shape Memory Alloy after Pre-Deforming

Cited by 5 publications

References 8 publications

Role of dislocations on martensitic transformation temperatures and microstructure: A molecular dynamics study

Role of dislocations on martensitic transformation temperatures and microstructure: A molecular dynamics study

Effects of Ambient Temperature and Ni-content on Function Deterioration Process of Ti-Ni Shape Memory Alloy

Effect of Heat-treatment Time on Performance Recovery of Ti-50.4at%Ni Shape Memory Alloy

Contact Info

Product

Resources

About