Crystal structure of stress-induced acicular martensite in Cu-14·2 al-4·3 Ni alloy

Abstract

The crystal structure of stress-induced acicular martensite in Cu-14·2 Al-4·3 Ni (w/o) alloy was determined by the method of electron microscopy and selected-area electron diffraction. It has been shown that the stress-induced acicular martensite is different from the thermally formed martensite not only in morphology but also in crystal structure. The structure was the same as that of thermally formed β₁’ martensite found in Cu–Al alloy with composition range 11 ∼ 13 (w/o) Al, and its lattice parameters were a = 4·382 Å, b = 5·356 Å and c = 38·00 Å. Thus, it is suggested that the effect of stress on martensitic transformation may be different from that of supercooling.