Dynamic Tensile Extrusion Behavior of Fine-Grained OFHC Cu Fabricated by Powder Injection Molding and Equal Channel Angular Pressing

The dynamic tensile extrusion (DTE) behavior and microstructural evolution of fine-grained (FG, ~1 μm < d < ~10 μm) Cu fabricated by powder injection molding (PIM) and equal-channel angular pressing (ECAP) were investigated. The FGM Cu was fabricated by PIM with commercial micro-sized Cu powder sintering at 850 °C for 2 h, while the FGH Cu was developed by the hot isostatic pressing of the FGM at 780 °C for 2 h under a pressure of 1000 bar. In order to compare the DTE behavior of the FG Cu depending on the manufacturing process, the ultrafine-grained-B (UFG-B, d < ~1 μm) Cu was developed by performing 16 passes of ECAP with route B_c, and the FG-150 and FG-200 Cu were fabricated by annealing the UFG-B Cu bar at 150 °C and 200 °C for 1 h, respectively. The DTE tests were performed with identical flyer velocities using an all-vacuum gas gun. The fragments and remnants were carefully recovered after the DTE tests and examined by EBSD measurement and a micro-Vickers hardness test. In order to compare microstructure evolution during the DTE deformation, an analysis of misorientation distribution and grain orientation spread was carried out from EBSD results. In addition, fracture characterization was accompanied by an investigation of the DTE fragments’ morphology.