Evolution of Microtexture and Microstructure During Sintering of Copper

Abstract

In the present investigation, the evolution of microstructure and microtexture of pure copper powder during solid state sintering was studied. The powder was compacted using 300 MPa uniaxial die pressure, and the green compact was sintered in an electric furnace at 610 °C, 880 °C, and 1020 °C in hydrogen atmosphere. The temperatures were selected to obtain different dominant densification processes comprised of grain boundary diffusion, surface diffusion, and volume diffusion, respectively. Electron backscatter diffraction (EBSD) studies indicated that there is a distinct evolution of microtexture and microstructure in terms of evolution of grain boundary character distribution (GBCD), size, shape, and morphology of grains and pores. The sample sintered at 610 °C showed poor densification and mechanical properties along with weak random microtexture. However, the sample sintered at 1020 °C showed relatively stronger 〈101〉 fiber texture, better strength, and better hardness. In addition, that sample exhibited a lower fraction of Σ3 twin and high-angle grain boundaries in comparison to samples sintered at lower sintering temperatures. This is attributed to high sintering temperature stimulated bulk diffusion that facilitated migration of grain boundaries and elimination of pores. A detailed analysis of microstructure and grain boundary character indicated the possibility of attempting grain boundary engineering during sintering for optimum processing and property enhancement.