scholarly journals FCC/HCP Martensitic Transformation and High-Temperature Shape Memory Properties in Co-Si Alloys

2006 ◽  
Vol 47 (9) ◽  
pp. 2377-2380 ◽  
Author(s):  
Toshihiro Omori ◽  
Wataru Ito ◽  
Keisuke Ando ◽  
Katsunari Oikawa ◽  
Ryosuke Kainuma ◽  
...  
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Memory Properties

Effect of the Addition of Gd on Ni53Mn22Co6Ga19 High-Temperature Shape Memory Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 2095-2098
Author(s):  
Yun Qing Ma ◽  
Shui Yuan Yang ◽  
San Li Lai ◽  
Shi Wen Tian ◽  
Cui Ping Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Earth Element ◽  
Stress And Strain ◽  
Martensitic Transformation Temperature ◽  
Rich Phase ◽  
Shape Memory Properties

The rare earth element Gd is added to Ni53Mn22Co6Ga19 high-temperature shape memory alloy to refine the grain size and adjust the distribution of γ phase, and their microstructure, martensitic transformation behaviors, mechanical and shape memory properties were investigated. The results show that the grain size is obviously decreased and the γ phase tends to segregate at grain boundaries with increasing Gd content. Small amounts of Gd-rich phase were formed with 0.1 at.% Gd addition. The martensitic transformation temperature abruptly increases with 0.1 at.% Gd addition, then almost keeps constant with further increasing Gd content. The addition of 0.1 at.% Gd is proved to be beneficial to both tensile stress and strain before fracture, but negative to the shape-memory effect.

scholarly journals Effect of Stoichiometry on Shape Memory Properties and Functional Stability of Ti–Ni–Pd Alloys

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 798 ◽  
Author(s):  
Yuki Hattori ◽  
Takahiro Taguchi ◽  
Hee Kim ◽  
Shuichi Miyazaki
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Stoichiometric Composition ◽  
Atomic Ratio ◽  
Transformation Temperatures ◽  
Shape Memory Properties ◽  
Ti Content

Ti–Ni–Pd shape memory alloys are promising candidates for high-temperature actuators operating at above 373 K. One of the key issues in developing high-temperature shape memory alloys is the degradation of shape memory properties and dimensional stabilities because plastic deformation becomes more pronounced at higher working temperature ranges. In this study, the effect of the Ti:(Ni + Pd) atomic ratio in TixNi70−xPd30 alloys with Ti content in the range from 49 at.% to 52 at.% on the martensitic transformation temperatures, microstructures and shape memory properties during thermal cycling under constant stresses were investigated. The martensitic transformation temperatures decreased with increasing or decreasing Ti content from the stoichiometric composition. In both Ti-rich and Ti-lean alloys, the transformation temperatures decreased during thermal cycling and the degree of decrease in the transformation temperatures became more pronounced as the composition of the alloy departed from the stoichiometric composition. Ti2Pd and P phases were formed during thermal cycling in Ti-rich and Ti-lean alloys, respectively. Both Ti-rich and Ti-lean alloys exhibited superior dimensional stabilities and excellent shape memory properties with higher recovery ratio and larger work output during thermal cycling under constant stresses when compared with the alloys with near-stoichiometric composition.

Stability of Ti-Ta Base High Temperature Shape Memory Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1921-1924 ◽  
Author(s):  
Hee Young Kim ◽  
Takafumi Kanaya ◽  
Tatsuhito Fukushima ◽  
Pio John S. Bueconsejo ◽  
Shuichi Miyazaki
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Thermal Cycling ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Aging Effect ◽  
Cyclic Stability ◽  
Martensitic Transformation Temperature ◽  
Shape Memory Properties ◽  
The Stability

The stability of shape memory properties was investigated by thermal cycling tests in Ti-23Ta-(2-4)Sn alloys. The martensitic transformation temperature decreased considerably after aging at 573 K for the Ti-23Ta-2Sn alloy. The decrease in the martensitic transformation temperature by the aging effect was suppressed by the addition of 3at.%Sn and more to the Ti-23Ta alloy. The Ti-23Ta-3Sn alloy exhibited better cyclic stability compared with a Ti-32Ta alloy which has a similar transformation temperature.

Martensitic transformation and shape memory properties of Ti–Ta–Sn high temperature shape memory alloys

2011 ◽  
Vol 528 (24) ◽  
pp. 7238-7246 ◽  
Author(s):  
Hee Young Kim ◽  
Tatsuhito Fukushima ◽  
Pio John S. Buenconsejo ◽  
Tae-hyun Nam ◽  
Shuichi Miyazaki
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Properties

Transformation Temperatures, Shape Memory and Magnetic Properties of Hafnium Modified Ti-Ta Based High Temperature Shape Memory Alloys

2017 ◽  
Vol 36 (2) ◽  
pp. 113-119
Author(s):  
W.Q. Khan ◽  
Q. Wang ◽  
X. Jin
Keyword(s):  
High Temperature ◽  
Shape Memory ◽  
Alloy System ◽  
Heat Of Reaction ◽  
Transformation Temperatures ◽  
Dsc Measurements ◽  
Recovery Strain ◽  
Shape Memory Properties ◽  
Three Point Bend Test ◽  
Point Bend

AbstractIn this study the modification effect of Hf content on the shape memory properties and magnetic permeability of a 75.5-77Ti-20Ta-3-4.5Hf alloy system has been systematically studied by DSC, three-point bend test, vector network analyzer and XRD. The martensitic transformation temperature, heat of reaction and recovery strain increases with the increase of hafnium and tantalum content. A stable high temperature shape memory effect was observed (Ms = 385–390 °C) during the two thermal cycles between 20 °C and 725 °C. Transformation temperatures and heats of reaction were determined by DSC measurements. Recovery strain was determined by three-point bend testing. Also an alloy, 70Ti-26Ta-4Hf, with higher tantalum content was produced to observe the effect of Ta on the shape memory properties. Permeability increases gradually from 1.671 to 1.919 with increasing content of hafnium modification and remains stable in the frequency range of 450 MHz to 1 GHz.

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.

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