The effects of substitution of yttrium for Ce-rich mischmetal on the mechanical properties and thermal conductivity of Mg–4Al–4Zn–4RE alloy.

Mechanical properties and thermal conductivity are the key parameters for Mg alloys used as the structural components for heat dissipation, balancing good mechanical properties and high thermal conductivity is still a long-term challenge. Here, we investigated the influence of Y contents on the microstructure and mechanical properties of the as-cast Mg–4Al–4Zn–(4– x)RE– x Y (x : 0, 1, 2, 3, 4 wt%), where RE was the Ce-rich misch metal. Compared with Mg–4Al–4Zn–4RE alloy, the strength and ductility were significantly enhanced due to the well-optimized microstructure by the suitable substitution of Y for Ce-rich RE. Especially, the ultimate tensile strength and elongation were significantly improved from 201 MPa to 244 MPa and 8.0% to 16.8%, respectively, when the Y content was increased from 0 to 3.0 wt%. Meanwhile, the thermal conductivity still kept a high level within the range of 84.2–89.6 W(m·K)−1. The significantly improved elongation was mainly attributed to the reduction and refinement of coarse lamellar Al 11 RE 3 intermetallic phases with increasing Y contents. The as-cast Mg–4Al–4Zn–1RE–3Y alloy exhibited high performance with a combination of high tensile properties and good thermal conductivity. [Display omitted] • The substitution of Y for Ce-rich RE tailored microstructure and enhanced tensile properties of the as-cast AZE444 alloy. • The tensile strength and elongation were significantly improved by the suitable substitution. • The as-cast Mg–4Al–4Zn–(4– x)RE– x Y also possessed high thermal conductivity within range of 84.2–89.6 W(m·K)−1. [ABSTRACT FROM AUTHOR]