Extruded Mg97.37Zn1.88Y0.75 alloy with both high thermal conductivity and mechanical strength

• The Mg 97.37 Zn 1.88 Y 0.75 (at%) alloy simultaneously possessing high thermal conductivity (131 Wm -1 K -1 ), high tensile yield strength (361 MPa), and notable elongation (9.7 %) was developed. • Regardless of the extrusion conditions, the extrusion processing moderately reduced the thermal conductivity of the alloy by about 10 ± 1 Wm -1 K -1 . • To achieve a favorable combination of high strength and ductility, it is essential to both refine the dynamic recrystallized grain structure and maximize its area fraction. • Optimizing the composition, heat treatment conditions, and extrusion conditions of the Mg alloy with a large negative mixing enthalpy of the added element pair may become a new guideline for developing Mg alloys with high thermal conductivity and mechanical strength. In our previous study, we observed that the Mg 97.37 Zn 1.88 Y 0.75 (at%) alloy, composed of α-Mg, the W phase (Mg 3 Zn 3 Y 2 ), and a small quantity of the I phase (Mg 3 Zn 6 Y) exhibited an extremely high thermal conductivity of 141 Wm -1 K -1 attributable to the precipitation of a large amount of the fine W phase through heat treatment at 633 K for 15 h. In the present study, we examined how extrusion conditions affect the thermal conductivity and mechanical properties of the Mg 97.37 Zn 1.88 Y 0.75 alloy with high thermal conductivity. As a result, an extruded Mg alloy was developed, exhibiting excellent properties, including a thermal conductivity of 131 Wm -1 K -1 , a tensile strength of 361 MPa, and an elongation of 9.7 %. These superior mechanical properties were obtained by optimizing extrusion conditions, thereby inducing dynamic recrystallization during the process to refine the α-Mg matrix and causing the dynamically recrystallized area, which consisted of grains with lower strain and random orientation, to expand. Furthermore, a decline in thermal conductivity by 9–11 Wm -1 K -1 was observed following extrusion, independent of the specific processing parameters.