Effect of Al content on microstructure, thermal conductivity, and mechanical properties of Mg-La-Al-Mn alloys

In this study, the microstructure, thermal conductivity, and mechanical properties of Mg-4La-xAl-0.5Mn (x = 0, 0.5, 1, 1.5, 2, and 2.5 wt%) alloys were investigated. As the Al content of the alloys increases, the continuous network Mg12La phase is gradually replaced by non-network Al-La phases. The types of Al-La phases depend on the Al content. When the Al content is relatively low, the alloy tends to form Al2La or Al53La22 phases; otherwise, it tends to form an Al11La3 phase. The concentration of the Al solute atoms in the alpha-Mg matrix increases gradually as the Al content increases. The thermal conductivity is very sensitive to the concentration of Al solute atoms. The thermal conductivity of high-pressure die cast Mg-4La-2.5Al-0.5Mn alloy is 106.5 W/(m.k) and its yield stress, tensile strength, and elongation are 149 MPa, 253 MPa, and 11.5%, respectively.

Automated summary

This study found that as the aluminum content in the alloy increases, the microstructure changes, thermal conductivity increases, and mechanical properties also change.