Effect of intermetallic compound thickness on anisotropy of Al/Cu honeycomb rods fabricated by hydrostatic extrusion process

The effect of intermetallic compound (IMC) thickness on the thermal and mechanical properties of Al/Cu honeycomb rods was investigated. The Al/Cu honeycomb rods were fabricated using repeated hydrostatic extrusions at 200 °C. During the process, an IMC layer with 1 μm in thickness was generated at the Al/Cu interface. Different IMC thicknesses were obtained by post-heat treatment at 420 °C for 0.5 to 2 h. The IMC thickness increased to 10.1 μm. The IMC layers were identified as Al2Cu (θ), AlCu (η2), and Al4Cu9 (γ1) phases. The thermal conductivities in the longitudinal direction and cross direction decreased by 11.9% ((268±4.8) to (236±4.4) W/(m·K)) and 10.4% ((210±3.2) to (188±2.8) W/(m·K)), respectively, with increasing IMC thickness. The ultimate tensile strength and elongation of the Al/Cu honeycomb rod are (103±8.4) MPa and (73±6.2)%, respectively. The ultimate tensile strength increased to (131±6.5) MPa until the IMC thickness reached 7.7 μm. It subsequently decreased to (124±3.9) MPa until the IMC thickness reached 10.1 μm. The elongation of the Al/Cu honeycomb rod then sharply decreased to (29±2.5)% with increasing IMC thickness.