Effects of Y on microstructure and property of heat treated AZ91D magnesium alloy prepared by lost foam casting process

Abstract

As cast AZ91D and AZ91D+1·0 wt-%Y magnesium alloy were prepared by the lost foam casting process and then treated by solution and aging treatment. The effects of Y on the microstructure and mechanical properties of heat treated AZ91D magnesium alloy were investigated. The results show that the addition of Y to AZ91D alloy formed the Al2Y phase, which still existed after solution treatment. During the aging treatment process, the rate of β-Mg17Al12 phase precipitating in AZ91D+1·0 wt-%Y alloy was much slower than in AZ91D alloy because the formation of Al2Y phase led to the depletion of Al atoms. The addition of Y was thus claimed to play a key role in delaying the age hardening peak on AZ91D alloy.