Mechanical and asymmetrical thermal properties of Al/Cu composite fabricated by repeated hydrostatic extrusion process

Abstract

In this work, an Al/Cu composite was fabricated using repeated hydrostatic extrusions with a semi-die angle of 45° at a temperature of 200°C. During the repeated hydrostatic extrusion process, an intermetallic layer of 1 μm was generated at the Al/Cu interface. The intermetallic reinforcement layer formation was studied via field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. The reinforcement layers consisted of Al₂Cu and Al₄Cu₉ phases. The thermal conductivity and coefficient of thermal expansion of the Al/Cu composites were determined via laser flash analyzer and thermal mechanical analyzer. The thermal conductivities in the longitudinal direction and cross direction were 267.8 W/mK and 209.9 W/mK at room temperature, respectively. The coefficient of thermal expansion at temperatures between room temperature and 450°C was 18.3 μm/m°C. The ultimate tensile strength of the Al/Cu composite is 102.8 MPa. The anisotropic physical properties of the prepared composite were mainly a result of the unique directional microstructure formed during the repeated extrusion process.