Age Hardening Behavior of Wrought Al-Mg-Sc Alloy

摘要

Ageing of Al-6Mg alloy doped with varying concentration of scandium ranging from 0.2 wt percent to 0.6 wt percent has been carried out. Cold-rolled alloy samples are isochronally aged for 60 minutes at different temperatures. The cast and hot-rolled samples are also aged isochronally for 90 minutes at different temperatures up to 450 deg C. Isothermal ageing of cold-rolled samples is conducted at various temperatures for different periods of time ranging from 30 to 480 minutes. Hardness values of the differently processed alloys have been measured to understand the ageing behavior of Al-6Mg alloy with scandium addition. The hot-rolled alloys after ageing do not show any hardening response due to ageing. Ageing of cold-rolled alloys envisaged precipitation of Al_3Sc which is not noted to be dislocation induced. The kinetics of precipitation of Al_3Sc in Al-6Mg-Sc alloys are found to be controlled by the diffusion of scandium in aluminum.