Thermocompression Deformation Behavior and Mechanism of Ni60Ti40 Alloy

The high-temperature deformation behavior of Ni60Ti40 alloy and the related mechanisms were investigated by thermocompression simulation experiments. The results of high-temperature compression tests were analyzed to reveal the effects of deformation temperature and strain rate on the structural properties and microstructure of alloys. Subsequently, the changing laws of the strain rate sensitivity index m, and the activation energy Q of alloys under different deformation conditions were obtained by calculation. Thermal processing maps based on the dynamic material model and the deformation mechanism maps revealing the dislocation quantity were plotted based on five plastic instability criteria, namely, Prasad, Gegel, Malas, Murty, and Semiatin, to analyze the physical significance of the parameters. The preferred forming zone and the rheological instability zone of the alloys were predicted using the thermal processing theories. The dislocation evolution laws and deformation mechanisms of the grain size with Burgers vector compensation were reported. With the aid of deformation maps, the rheological stress combined with modulus compensation during the high-temperature superplastic deformation was predicted. Copyright © 2021, Northwest Institute for Nonferrous Metal Research. Published by Science Press. All rights reserved.