The solution and aging behavior of Mg-8Li-3Al-xCe(x = 0, 1.0) alloys

Abstract

The microstructure and microhardness properties of the as-cast, as-soluted and as-aged alloys of Mg-8Li-3Al-xCe(x = 0, 1.0) were investigated. The as-cast Mg-8Li-3Al (LA83) alloy consists of α-Mg, β-Li, AlLi and MgLi2Al phases. The as-cast LA83-1Ce alloy consists of α-Mg, β-Li, MgLi2Al, AlCe and Al2Ce phases. Besides, the addition of Ce can refine and spheroidize the microstructure of as-cast LA83 alloy. After the addition of Ce, the HV of α and β phases were improved by 137 % and 127 %, respectively, and the HV value difference between α and β became small. Heat treatment can raise the alloy-HV, α-HV and β-HV of LA83 and LA83-1Ce alloys. The variation in hardness during aging process is attributed to the precipitation of MgLi2Al phase and the possibility of the transformation from AlLi phase to MgLi2Al phase. With the increase of aging temperature, the size of MgLi2Al phase becomes larger apparently, causing the age softening phenomenon happens.