Investigation of Formation Behaviour of Al–Cu Intermetallic Compounds in Al–50vol%Cu Composites Prepared by Spark Plasma Sintering under High Pressure

Abstract

Al–Cu matrix composites with excellent mechanical and thermal properties are among the most promising materials for realising high performance in thermal management systems. However, intermetallic compounds (ICs) formed at the Al/Cu interfaces prevent direct contact between the metals and severely deteriorate the thermal conductivity of the composite. In this study, we systemically investigated the formation behaviour of Al–Cu ICs as a function of compaction pressure at a low temperature of 380 °C. The phases of the Al–Cu ICs formed during sintering were detected via X-ray diffraction, and the layer thickness and average area fraction of each IC at different compaction pressures were analysed via micro-scale observations of the cross-sections of the Al–Cu composites. The ICs were partially formed along the Al/Cu interfaces at high pressures, and the formation region was related to the direction of applied pressure. The Vickers hardness of the Al–Cu composites with ICs was nearly double those calculated using the rule of mixtures. On the other hand, the thermal conductivity of the composites increased with compaction pressure and reached 201 W·m−1·K−1. This study suggests the possibility of employing Al–Cu matrix composites with controlled IC formation in thermal management applications.