Effects of mixing methods on the interface and microstructure evolution of graphene platelets/Ti-6Al-4V powder composites fabricated by powder metallurgy and extrusion

Abstract

Graphene nanoplatelets (GNPs)/Ti6Al4V composites were fabricated by pre-sintering and canned extrusion. Three composite powders with different GNPs defect densities and different GNPs dispersion effects were obtained by adjusting the mixing process of spherical Ti6Al4V powders and GNPs. Higher GNPs defect density induced more severe interface reaction, leading to more TiC particles. The interfacial bonding between graphene and matrix was affected by the increase and growth of TiC particles. As a result, the strength of the composites increased, and the strains decreased. Electron backscatter diffraction (EBSD) was used to investigate the microstructure evolution of the matrix. Due to the particle stimulated nucleation (PSN) mechanism, GNPs promoted recrystallization in the surrounding matrix. In addition, the recrystallization process of the TMCs was influenced by GNPs. With the increase of the GNPs dispersion effect, more recrystallized nucleation was formed in the matrix, which increased the content of equiaxed grains from 29.9% to 39.1%. This article provides new insight into adjusting the interface and microstructure of GNPs/Ti6Al4V composites.