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

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 degrees C x 0.5 h, the MgLi2Al phase is dissolved in the phase of beta-Li, and the AlLi phase precipitates from alpha-Mg phase. With the holding time being prolonged to 1 h, the precipitated AlLi distributes in the whole phase of a-Mg. Under the condition of 440 degrees C x 0.5 h, the AlLi phase is dissolved in the matrix, and MgLi2Al phase precipitates from beta-Li. The addition of 2 wt.% 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. (C) 2013 Elsevier Ltd. All rights reserved.