Deformation mechanism and enhanced properties of Cu–TiB2 composites evaluated by the in-situ tensile test and microstructure characterization

Abstract

The demand for using high-performance Cu matrix composites in the electronic industry has recently increased rapidly owing to the low strength and tribological properties of pure copper. Accordingly, research and development of composite processing and related properties have increased. In this study, the Cu matrix was reinforced with different amounts of TiB2 particles by mechanical alloying of elemental powders followed by consolidation employing spark plasma sintering (SPS) whereby high relative density (∼99%) and electric conductivity (∼83–88% IACS) were obtained. Tensile properties and deformation mechanisms of the composites were studied utilizing conventional and in-situ tensile tests with simultaneous FESEM and EBSD observations. In comparison with the reference pure copper, it was found that adding 0.5 wt%TiB2 results in significant ductility increment, which was consistent with the longer strain-softening behavior observed after necking. In addition, using in-situ microstructure characterization, twinning with slip bands were confirmed as deformation mechanisms. By increasing the amount of reinforcement to 5 wt%TiB2, strengthening was remarkable while sustaining a considerable elongation. The Hall-Petch and dislocation strengthening mechanisms were the key models of strengthening based on the calculations and microstructure characterizations since by increasing the TiB2 particles, significant grain refinement and dislocation density were shown.