Mechanical Twinning in Copper-29.9 at. Gold Single Crystals

摘要

Abstract Three copper-gold single crystals containing 29.9 at. % gold and having the disordered, Cu3Au I and Cu3Au II structure respectively, were deformed in tension at room temperature, at dry ice temperature (just into the plastic region) and at liquid nitrogen temperature (until fracture) successively.For Cu3Au I and Cu3Au II 00 does not vary practically with composition, being four times that of stoichiometric Cu3Au [6]. At 78° K twinning was observed in the elastic region for Cu3Au II, whereas Cu3Au I twinned only under the influence of complex stresses; the disordered alloy showed no twinning at all.The strain-hardening II at 78° K is almost the same for Cu3Au I and Cu3Au II at the 20.9 at. % composition.