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 ß-HV of LA83 and LA83-1Ce alloys. The variation in hardness during aging process is attributed to the precipitation of MgLi₂Al and the possibility of the transformation from AlLi to MgLi₂Al phase. With the increase of aging temperature, the size of MgLi₂Al phase becomes larger apparently, causing the age softening phenomenon happens.

Key words
Mg-Li alloy, Ce, aging behavior microhardness, microstructure

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