HIGH-RESOLUTION ELECTRON-MICROSCOPY OBSERVATION OF THE FINE-STRUCTURE OF CU-ZN-AL MARTENSITES

The fine structure of martensites in step-quenched Cu-17.4 at.% Zn-13.0 at.% Al alloy has been observed using high-resolution electron microscopy. It has been found that, besides the 18R1 martensite occurring most frequently, there exist also 6R and 2H martensites in local regions. Stacking faults, extended dislocations with Burgers vector 1/4[210]6R and basal plane twins have also been observed in 6R martensite. The planarity and coherency of the (2, 0, 20)18R1 A-D twin boundary of 18R1 martensite are much less than those of the (128BAR)18R1 A-C twin boundary. Edge dislocations, whose Burgers vector has a component in the [001]18R1 direction, have been observed near the (2, 0, 20)18R1 boundary.