Plastic deformation of the intermetallic compound Al₃Ti

Abstract

Polycrystalline specimens of the intermetallic compound Al₃Ti with the D0₂₂-type structure have been deformed under compression at 25–860°C. At temperatures below 620°C, specimens fracture with very small fracture strain since extremely localized deformation occurs and cracks are initiated in intensely deformed regions almost at yielding. At temperatures above 620°C, good compression ductility is observed. Yield stress starts decreasing rapidly with increasing temperature at around 330°C and becomes less temperature dependent above 630°C.

The major mode of deformation of Al₃Ti is twinning of the type (111)[112] which does not disturb the D0₂₂ symmetry of the lattice. However, at high temperatures, the four (111)[112]-type twinning systems are augmented by slip of the types [110], [100] and [010]. This would supply an explanation for the good compression ductility observed at temperatures above 620°C. Suggestions are made for further experimental work on alloying additions which may improve the ductility of Al₃Ti.