Effect of Post-annealing on Grain Boundary of Nano-crystalline Cu Processed by Powder High-Pressure Torsion

Abstract

High tensile strength of 616 MPa and improved ductility of 7.6 pct were obtained in powder-consolidated pure Cu processed by high-pressure torsion (HPT) at room temperature followed by post-annealing at 673 K (400 A degrees C). The powder-HPT consolidation process maintained nano-crystalline microstructures even after post-annealing due to the presence of well-dispersed oxide particles in the matrix. Higher ductility in the post-annealed specimen is attributed to higher fraction of stable I 3 pound coincidence site lattice boundaries than that in the HPT-processed Cu.