A detailed study of phase evolution in Cu-16 at. %Al and Cu-30 at. %Al alloys under different types of mechanical alloying processes

Abstract

The phase stability of Cu-16 at. %Al and Cu-30 at. %Al alloys obtained by a planetary and an horizontal mills was investigated. The analysis was carried out using X-ray diffraction and various transmission electron microscopy (TEM) techniques. X-ray diffraction analysis gives a statistical overview of the main equilibrium phases present. Meanwhile, the different TEM techniques allow the detection of either the minor phases or the ones having crystalline domains smaller than 5 nm. The solid solution equilibrium α phase was obtained using both milling processes on the Cu-16 at. %Al. Instead, the final intermetallics observed for Cu-30 at. %Al were not the equilibrium ones according to the phase diagram. The planetary mill produced a mixture of α and γ2 phases and less than a 2 at. % of β phase. The horizontal mill produced a γ2 phase and less than a 2 at. % of α2 and γÍ phases. For both compositions, the horizontal mill seems to be more efficient to achieved the equilibrium intermetallic compound.