Transformation behavior and shape memory properties of Ti 50 Ni 15 Pd 25 Cu 10 high temperature shape memory alloy at various aging temperatures

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.

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Martensitic Transformation Behavior and Shape Memory Effect of an Aged Ni-rich Ti-Ni-Hf High Temperature Shape Memory Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.138.399 ◽

2008 ◽

Vol 138 ◽

pp. 399-406 ◽

Cited By ~ 3

Author(s):

Xiang Long Meng ◽

Yu Dong Fu ◽

Wei Cai ◽

J.X. Zhang ◽

Qing Fen Li ◽

...

Keyword(s):

High Temperature ◽

Martensitic Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Shape Memory Effect ◽

Memory Effect ◽

Aging Temperature ◽

Transformation Behavior ◽

Transformation Temperatures ◽

Solution Treated

The martensitic transformation behavior and shape memory effect (SME) have been investigated in a Ni-rich Ti29.6Ni50.4Hf20 high temperature shape memory alloy (SMA) in the present study. After aging, the transformation temperatures of Ti29.6Ni50.4Hf20 alloy increase obviously due to the precipitation of (Ti,Hf)3Ni4 particles. And the transformation sequence changes from one-step to two-step. When the experimental alloy is aged at different temperatures for 2h, the transformation temperatures increase rapidly with increasing the aging temperature and then change slightly with further increasing the aging temperature. Most of the martensite variants preferentially oriented in the aged Ti29.6Ni50.4Hf20 alloy. The aged Ti29.6Ni50.4Hf20 alloy shows the better thermal stability of transformation temperatures than the solution-treated one because the precipitates depress the introduction of defects during thermal cycling. In addition, the proper aged Ti29.6Ni50.4Hf20 alloy also shows the larger SME than the solution-treated one since the precipitates strengthen the matrix strongly.

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Characteristics of Ti50-Pd(50-x)-W(x) High Temperature Shape Memory Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.3190 ◽

2007 ◽

Vol 539-543 ◽

pp. 3190-3194 ◽

Cited By ~ 2

Author(s):

Hiroyuki Nakayama ◽

Minoru Taya

Keyword(s):

High Temperature ◽

Shape Memory Alloy ◽

Shape Memory ◽

Cooling Curve ◽

Bending Test ◽

Rolled Plate ◽

Electrical Resistivity Measurement ◽

Transformation Behavior ◽

Alloy Plate ◽

Hot Rolled

Characteristics of high temperature shape memory alloy in Ti50-Pd(50-x)-W(x) at%, x = 3 and 5 system has been examined. The prepared ingot was homogenized at 1273 K for 86.4 ks followed by water quenched. The homogenized samples were hot-rolled at 1273 K to a plate shape with thickness of 3.5 mm and 1.0 mm. Transformation temperatures were determined by 4-probe electrical resistivity measurement. The transformation behavior in the both samples exhibited similar trend. The first heating curve showed no significant step. In contrast, the first cooling curve exhibited clear step due to martensitic transformation. After second cycle, the transformation behavior was stabilized, thus the clear steps in the cooling and heating curves were seen. Stressstrain curve of hot-rolled plate with 3.5 mm was examined by compression in Ti50-Pd47-W3 at% alloys. The sample exhibited 1 % shape memory effect. By bending test, nearly perfect SME effect was observed in hot rolled Ti50-Pd45-W5 at% alloy plate with thickness of 1 mm.

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Effects of High Temperature ECAE Process on Microstructures and Martensitic Transformation of TiNi Shape Memory Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.1013 ◽

2006 ◽

Vol 503-504 ◽

pp. 1013-0 ◽

Cited By ~ 11

Author(s):

Chao Ying Xie ◽

Z.G. Fan ◽

Z.H. Li ◽

G.Q. Xiang ◽

X.H. Cheng

Keyword(s):

Phase Transformation ◽

High Temperature ◽

Martensitic Transformation ◽

Shape Memory Alloy ◽

Shape Memory ◽

Tini Alloy ◽

Behavior Changes ◽

Transformation Behavior ◽

Coarse Grains ◽

Short Annealing

Microstructures and transformation behavior of TiNi shape memory alloy after high temperature ECAE process have been investigated. It is found that the initial coarse grains were refined after high temperature ECAE processes and short annealing at 750°C. Transformation temperatures of TiNi alloy sharply decreased after two ECAE processes, rose obviously when annealed at 750°C for 5min, and quickly rose back after annealing at 500°C for 2 hours. Reasons for phase transformation behavior changes have been discussed.

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A Study on Shape Memory Performance of Cu-Al-Ni-Be Alloy Single Crystal

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.21 ◽

2011 ◽

Vol 287-290 ◽

pp. 21-25

Author(s):

Hua Ping Xu ◽

Gao Feng Song ◽

Xie Min Mao

Keyword(s):

High Temperature ◽

Temperature Gradient ◽

Shape Memory Alloy ◽

Single Crystal ◽

Shape Memory ◽

Directional Solidification ◽

Memory Performance ◽

Copper Base ◽

Shape Memory Properties ◽

Solidification Furnace

In this paper, single crystal of CuAlNiBe quaternary shape memory alloy was prepared in a high temperature gradient directional solidification furnace with a selective growing crystallizer. And its shape memory performance characters were systematically compared with other series copper base shape memory alloys. The results show that the single crystal of CuAlNiBe quaternary shape memory alloy has better shape memory properties.

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