Microstructure and compressive properties of in situ synthesized Ti–Si alloy composites reinforced with La2O3 particles

The Ti–5.5Si alloy composites reinforced by La2O3 particles were prepared through the synthesis reaction from Ti, Si, La and SiO2 with non-consumable vacuum arc melting. The microstructures were examined by means of optical microscopy (OM), backscattered scanning electron microscopy (SEM). The phase analysis was identified by X-ray diffraction (XRD). There are four phases in the composite, namely Ti5Si3, La2O3, α-Ti and β-Ti. In the microstructures of those composites, the continuous and quasi-continuous network-shape Ti5Si3 + Ti eutectic cell abundantly exists, and the La2O3 reinforcement grows from near-equiaxed shape to dendritic shape with increase of La content. The compressive properties of the as-cast composites were tested with strain rate 1 mm/min at room temperature. The results showed that the introduction of in situ La2O3 particles can significantly improve the compressive strength and the Young's modulus of Ti–5.5Si alloy.