Phase transformations in creep resistant MgYNdScMn alloy

Abstract

Abstract Mg-4 wt.% Y-2 wt.% Nd-1 wt.% Sc-1 wt.% Mn alloy was squeeze-cast. It benefited from the addition of Nd which decreased the solubility of Y in Mg, as is known from WE alloys. Isochronal annealing of the alloy showed relative resistivity changes similar to those obtained in other Mg–R.E.–Sc–Mn alloys (R.E. – rare-earth element). The resistivity decrease observed is due to the complex precipitation process, namely a combination of decomposition sequences in the Mg–Y–Nd, Mg–R.E.–Mn, and Mn–Sc systems. The increase in the resistivity on isochronal annealing up to temperatures over 500 °C is due to the re-solution of the phases in the first two systems. The Mn2Sc phase coarsens only during this annealing treatment. The creep resistance of the alloy at high temperatures is better than that of low Sc content Mg alloys with Yand Gd in the T5 condition and also than that of WE alloys in the T6 condition.