Effect of spark plasma sintering temperatures on microstructure and mechanical properties of in-situ (La2O3+TiB)/Ti2AlNb composites with a tailored three-dimensional network architecture

The influence of sintering temperatures on the microstructure and properties of network-strengthened (La2O3+TiB)/Ti2AlNb composites were investigated in this study. Microstructural characterization results showed that the reinforced phases comprised of B27-type TiB and La2O3 would in-situ form with transition phases disappearing. Also, the TiB held a fixed crystallographic orientation relationship with alpha(2)-Ti3Al phase. The excess precipitation of alpha(2), voids and the agglomeration of reinforced phases in prior particle boundaries (PPBs) area were faded away with the sintering temperature increasing. Tensile test results demonstrated the composite sintered at 1250 degrees C exhibited a superior tensile strength of 1095 and 853 MPa at 25 and 650 degrees C, respectively. Pores, the agglomeration of the reinforced phases and massive alpha(2) in PPBs area would promote premature rupture and cause a low tensile strength. When the premature failure was avoided, a high TiB aspect ratio was favorable to strengthening.