High-temperature in-situ microscopy during stress-induced phase transformations in Co49Ni21Ga30 shape memory alloy single crystals
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This paper reports on the role of repeated stress-induced martensite transformations at different temperatures (referred to as "training") on the pseudoelasticity and microstructural evolution of as-grown Co 49Ni21Ga30 -oriented shape memory alloy single crystals under compression. The training resulted in a reduction in transformation stress levels and a stable microstructure with a multi-variant configuration reducing the observed transformation strains. Training also improved the recoverability giving way to a large pseudoelastic temperature window of 400 °C. In-situ microscopy revealed the martensite stabilization to be due to pinning of moving interfaces especially at temperatures above 120°C. An insight into the evolution of microstructure and stress-strain behavior in terms of stress hysteresis changes with test temperature is provided, and the possible operant mechanisms are discussed. © Carl Hanser Verlag GmbH & Co. KG ISSN 1862-5282.
author list (cited authors)
Dadda, J., Maier, H., Karaman, I., & Chumlyakov, Y.