Deformation of Al-2 wt.% Ge and Al-4 wt.% Ge alloys in the presence of precipitation of varying amounts

Abstract

Two Al-Ge alloys were tensile tested in the range 298 to 598 K to assess the effects of temperature, strain rate, grain size and composition on deformation in presence of precipitation. Independent of strain rate, grain size and composition, the ductility-test temperature curves went first through a maximum and then a minimum. The variations in the 0.2% yield stress, the ultimate tensile strength (UTS), the parabolic stress-strain relationship and the strain-rate sensitivity of flow were also recorded as functions of the experimental variables. Electron microscopy revealed that sub-grain formation was present from 298 K till the temperature of minimum ductility. Ge precipitation, whose size, quantity and morphology depended on the experimental conditions, was present in the temperature interval covered by the maximum and mini­ mum in ductility. Byond the temperature of ductility minimum, the precipitates and sub-grains were less frequently seen.