Strengthening of lotus-type porous copper by ECAE process

Lotus-type porous copper with directional cylindrical pores was fabricated by unidirectional solidification in a pressurized hydrogen atmosphere. Improvements in microstructure and mechanical properties of the lotus-type porous copper by equal-channel angular extrusion (ECAE) were investigated using a die with a channel angle of 150°. The porosity decreases with increasing pass number, and decreases from 46% to 30% by four passes. It means that pore closure in the ECAE process is not significant. Both the specific compressive yield strength image and the Vickers hardness HV of the lotus copper increase with increasing pass number of ECAE. The ECAE processed porous copper shows improved image and HV comparable to those of the extruded nonporous copper. It is suggested that ECAE is a promising method to strengthen porous metals without significant pore closure.