Phase Transition of Ball-Milled Ni_50-xMn₃₇In₁₃Co_x (x=0,5) Alloy Powders

Abstract

Ni50-xMn37In13Cox(x=0,5) alloy powders were obtained by ball-milling from the corresponding ribbon precursors. The as-milled Ni50Mn37In13and Ni45Mn37In13Co5powders show disorderedfctandfccstructures respectively, due to the larger lattice distortion in Ni45Mn37In13Co5. DSC and XRD results show that the high-temperature annealing will lead to a one-step ordering process fromfctto Heusler structure in Ni50Mn37In13, and a two-step ordering process, includingfcctobccandbccto Heusler phase transitions in Ni45Mn37In13Co5. After annealed at 400°C and 650°C, the martensitic transformation behavior is gradually and partially restored in Ni50Mn37In13powders. As modulated by the annealing temperatures, the martensitic transformation temperatures increase with the grain sizes of Ni50Mn37In13powders. However, the martensitic transformation is almost completely suppressed in 650°C annealed Ni45Mn37In13Co5powders with only some weak reflection peaks from 7M martensitic phase observed in XRD pattern.