Stacking Faults in the Martensite of Cu-Al Alloy

Electron diffraction patterns were taken of β' martensite of Cu–Al alloy containing 12.3 wt% of Al. The diffuseness and shifts of spots in these patterns were analysed by using equations derived from the general theory proposed by Kakinoki. Generally speaking, four parameters are necessary, in the case of the Reichweite s =3, for describing the probability of stacking faults on (001) planes, but the observed spectra can be interpreted, in the first approximation, by considering two parameters, α and β, which are related to the cubic and hexagonal stractures, respectively. The amount of relative shifts of spots gives α=0.004∼0.27 and β=0.12∼0.40, varying from crystal to crystal.