Realization of synergistic enhancement for strength, wear resistance and ductility via adding La2O3 particles in (TiB+TiC)/Ti6Al4V composite

Abstract

The hybrid of (TiB + TiC + La2O3) reinforced Ti6Al4V matrix composites (TMCs) were in-situ synthesized by non-consumable arc-melting technology. Effects of addition of La2O3 particles on microstructure evolution, thermal properties, mechanical properties and tribological behavior of the TMCs were investigated. The results indicated that incorporation of La2O3 particles could effectively reduce the average grain size of α-Ti and reinforced phases and increase the ratio of high angle grain boundaries (HAGBs), and grain orientation distribution exhibits more random. The TMCs with addition of La2O3 particles manifests more stable and higher thermal conductivity and lower coefficient of thermal expansion at high temperature. With addition of 0.4 vol% La2O3 particles, TMCs exhibits a near network structure and achieves the good combination of compressive strength (2203 MPa) and ductility (21.45%), which is mainly attributed to particle reinforcement and fine grain strengthening. Compared with TMCs without La2O3 particles, the specific wear rates of TMCs with an increase in La2O3 content from 0.2 vol% to 0.8 vol% reduce by 18.5%, 33.6%, 34.7%, respectively. The wear resistance is enhanced due to synergistic effect of the hetero-deformation induced strain-strengthening and the formation of dense and hard tribo-layer during friction. Significantly, the TMCs with addition of 0.4 vol% La2O3 particles has the best thermal, mechanical and tribological properties. This study may provide a pathway to improve simultaneously the mechanical properties and wear resistance of TMCs for engineering applications.