Microstructure and mechanical properties of Ti6Al4V/B₄C composite prepared by arc melting

Ti6Al4V/B₄C titanium matrix composites with different B₄C contents were prepared by vacuum arc melting. The microstructure and mechanical properties were characterized and analyzed by optical microscope, scanning electron microscope, microhardness tester, static compression and tensile test. The results show that in the process of arc melting, B₄C reacts with titanium matrix in situ to form TiB, TIC and TiB₂ phases. TiB presents one-dimensional long whisker shape, TiC presents granular shape, and massive TiB₂ is formed when the content of B₄C is 10 wt.%, and a special hollow prismatic Ti (B_xC_y) polymer may be formed. TiB₂ produced by in-situ reaction significantly improve the microhardness of titanium matrix composites. When the content of B₄C is 0.5 wt.%, the continuous network and evenly distributed structure of TiB and TiC produced by the in-situ reaction of titanium matrix composites has the best mechanical properties. The maximum compressive strength of the sample reaches 1 990 MPa and the maximum compressive strain is 35.5%. The compressive property exceeds that of molten titanium alloy. The tensile strength reaches 1 034 MPa, which is nearly 24% higher than that of molten titanium alloy, but the plasticity decreases. With the increase of B₄C content, the tensile strength decreases gradually, titanium matrix composites gradually change from ductile fracture to brittle fracture.