Influences of solid solution parameters on the microstrucuture and hardness of Mg–9Li–6Al and Mg–9Li–6Al–2Y

Abstract

The microstructure evolution of Mg–9Li–6Al and Mg–9Li–6Al–2Y with the variation of solid solution parameters was investigated. Results show that, in Mg–9Li–6Al, under the condition of 340°C×0.5h, the MgLi2Al phase is dissolved in the phase of β-Li, and the AlLi phase precipitates from α-Mg phase. With the holding time being prolonged to 1h, the precipitated AlLi distributes in the whole phase of α-Mg. Under the condition of 440°C×0.5h, the AlLi phase is dissolved in the matrix, and MgLi2Al phase precipitates from β-Li. The addition of 2wt.% Y in Mg–9Li–6Al can promote the precipitation of MgLi2Al phase and restrain the precipitation of AlLi phase, causing the increase of hardness of the alloy.