Microstructures and Phase Transformations of Ti-50.9at%Ni Alloy Processed by Equal Channel Angular Extrusion at Medium Temperature
Submicron-grained Ti-50.9at%Ni alloy was prepared by Equal Channel Angular Extrusion (ECAE) at medium temperature(500°C). Microstructure evolution and phase transformations of Ti-50.9at%Ni alloy after ECAE processes at medium temperature have been investigated by optical microscope, TEM and DSC tests. It is found that the initial coarse grains of Ti-50.9at%Ni alloy were refined into submicron grains, smaller than 0.5 um in size, after eight passes ECAE at 500°C. Martensitic transformation temperatures decreased remarkably after one pass ECAE and more gently with increasing the pass number of ECAE. R phase transformation was stimulated after ECAE processes and underwent within a larger temperature range with an ambiguous thermal peak. The reverse R phase and reverse martensitic transformations, during heating, were separated eventually after eight passes ECAE.
Young Won Chang, Nack J. Kim and Chong Soo Lee
C. Y. Xie and Z. G. Fan, "Microstructures and Phase Transformations of Ti-50.9at%Ni Alloy Processed by Equal Channel Angular Extrusion at Medium Temperature", Materials Science Forum, Vols. 561-565, pp. 877-880, 2007