scholarly journals Recent Development of TiNi‐Based Shape Memory Alloys with High Cycle Stability and High Transformation Temperature

2020 ◽  
Vol 22 (4) ◽  
pp. 1900496 ◽  
Author(s):  
Yunxiang Tong ◽  
Aleksandr Shuitcev ◽  
Yufeng Zheng
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Cycle Stability ◽  
High Transformation ◽  
High Transformation Temperature

Martensitic Transformation of High-Entropy and Medium-Entropy Shape Memory Alloys

2021 ◽  
Vol 1016 ◽  
pp. 1802-1810
Author(s):  
Hiromichi Matsuda ◽  
Masayuki Shimojo ◽  
Hideyuki Murakami ◽  
Yoko Yamabe-Mitarai
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Solid Solution Hardening ◽  
Solution Hardening ◽  
High Entropy ◽  
The One

As new generation of high-temperature shape memory alloys, high-entropy alloys (HEAs) have been attracted for strong solid-solution hardened alloys due to their severe lattice distortion and sluggish diffusion. TiPd is the one potential high-temperature shape memory alloys because of its high martensitic transformation temperature above 500 °C. As constituent elements, Zr expected solid-solution hardening, Pt expected increase of transformation temperature, Au expected keeping transformation temperature, and Co expected not to form harmful phase. By changing the alloy composition slightly, two HEAs and two medium entropy alloys (MEAs) were prepared. Only two MEAs, Ti45Zr5Pd25Pt20Au5, and Ti45Zr5Pd25Pt20Co5 had the martensitic transformation. The perfect recovery was obtained in Ti45Zr5Pd25Pt20Co5 during the repeated thermal cyclic test, training, under 200 MPa. On the other hand, the small irrecoverable strain was remained in Ti45Zr5Pd25Pt20Au5 during the training under 150 MPa because of the small solid-solution hardening effect. It indicates that Ti45Zr5Pd25Pt20Co5 is the one possible HT-SMA working between 342 and 450 °C.

Preparation by Twin Roll Casting and Characterization of TiNi Shape Memory Alloys Strips

2007 ◽  
Vol 130 ◽  
pp. 121-126 ◽  
Author(s):  
Richard Portier ◽  
Philippe Vermaut ◽  
Patrick Ochin ◽  
Tomasz Goryczka ◽  
Jorge Malarría
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Functional Properties ◽  
Plane Surface ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
High Transformation ◽  
Production Technologies ◽  
Twin Roll

The thermoelastic martensitic transformation which gives remarkable functional properties to Shape Memory Alloys (SMA) is very sensitive to the chemistry of the alloys and to its microstructure. In many cases, especially for alloys with high transformation temperatures, applications are limited by the poor ductility. To overcome the brittleness of SMA, one approach can be effective : the development of non conventional production technologies which enable to obtain materials in forms close to requirements: strips of SMA have been prepared by Twin Roll Casting (TRC). The formation of a solid sheet with plane surface is only possible for a limited combination of the different machine parameters and they will be discussed. For comprehension of the process parameters effect, the attention will be focused on TiNi. Microstructures and functional properties will be examined in relation with the microstructures induced by the technique or after specific thermal treatment.

Sign in / Sign up

Export Citation Format

Share Document