Deformation and fracture behaviour of the heusler alloy Cu 2MnAl single crystals

Abstract

Various orientations of single crystals of the Heusler alloy Cu 2MnAl have been tested in compression at 77–367 K. Slip occurs along 〈111〉 and the observed slip phane varies with crystal orientation. For orientations where slip of the {110}-type is activated, a sharp decrease in ductility occurs at around 240 K and below this temperature, fracture occurs explosively with practically no observable plastic deformation. For orientations exhibiting slip on {112} planes, on the other hand, crystals can be deformed plastically even at 77 K. The brittle fracture for the former orientations is probably triggered by the burst of coarse {110} slip bands. The occurrence of the coarse {110} slip appears to be explained in terms of the dissociation of superlattice dislocations which is characteristic of DO 3 and L2 1 structures.