Microscopic Observation of the Thermoelastic α′₂ Ni–Zn–Cu Martensite

Abstract

Ni_52−xZn₄₈Cu_x alloys undergo a martensitic transformation from the CsCl-type ordered cubic (β₂ phase) to the AuCuI-type ordered tetragonal (α′₂ phase). The thermoelastic nature of the martensitic transformation in Ni₃₂Zn₄₈Cu₂₀ alloy was observed by an optical microscope. The microstructure of the α′₂ Ni₃₄Zn₄₈Cu₁₈ martensite was investigated by transmission electron microscopy and found to be internal twinning on the {111}⟨11\bar2⟩_fct system.