Semi-Solid Casting of AlN Reinforced Mg-Matrix Composites and their Thermophysical Properties

Abstract

AlN has high thermal conductivity (TC) and low coefficient of thermal expansion (CTE), which is an ideal reinforcement phase for strengthening the thermophysical properties of magnesium alloys to be used as packaging substrate material. However, the poor wettability between AlN and magnesium melt makes the preparation of AlN/Mg composites with high AlN content very difficult. In this work, the AlN/Mg-5Zn-4.9Cu composites were prepared by semi-solid stir casting method to address this problem, and the effect of AlN particle content on the thermophysical properties of the composites was investigated. The results show that AlN can reduce the CTE of magnesium alloy significantly and weaken the TC of magnesium alloys slightly. When 20 wt.% of AlN was added, the TC of the composites was 125.1 W/(m·K) and the CTE was only 19.83×10-6 K-1, which was 26.7% lower than that of the matrix alloy.