High-temperature Pseudoelasticity of Co49Ni21Ga30 Shape Memory Alloy Single Crystals under Compression Conference Paper uri icon

abstract

  • Pseudoelasticity as a function of temperature and crystallographic orientation in Co49Ni21Ga30 single crystals was studied under compression. The pseudoelastic (PE) temperature window and its dependency on the Clausius-Clapeyron (CC) slope and the resolved shear stress factor (RSSF) for the phase transformation were revealed for as-grown 〈100〉, 〈123〉 and 〈235〉 orientations. A high RSSF value results in a low CC-slope, which in turn brought about a large PE window of 400°C for the 〈100〉 orientation. Thus, the effect of homogenization on crystals with this orientation was also investigated. Homogenization restored the single phase B2 austenite (β) from the dual phase (β + γ) as-grown crystals changing the chemical composition of the β-matrix, which lead to increase in the CC-slope. This in turn depressed the PE temperature window to 350°C. The results suggested that the pseudoelasticity of CoNiGa alloys can be tailored for specific elevated temperature applications by the selection of crystallographic orientation and heat treatment. Copyright © 2008 ASM International® All rights reserved.

author list (cited authors)

  • Dadda, J., Maier, H. J., & Karaman, I.

publication date

  • December 2008