Experimental investigation of tensile, fracture and fatigue crack growth behavior of LPBF-fabricated Ti-6Al-4V/TiC composites

In this study, the influence of TiC reinforcement content on the tensile and fatigue behavior of Ti-6Al-4V alloy fabricated using the Laser Powder Bed Fusion (LPBF) process was investigated. Ti-6Al-4V and Ti-6Al-4V/TiC composites with different wt.% of TiC were successfully produced and evaluated through tensile, fracture toughness, and fatigue testing. The results demonstrated that TiC reinforcement significantly improves the mechanical performance of the alloy. The maximum tensile strength of 1378.8 MPa was achieved, corresponding to a 15.3% increase compared to the base alloy, while the elastic modulus increased by 16.8%. However, ductility decreased markedly from 11.5% to 4.6% due to the presence of hard ceramic particles. Fracture toughness increased with TiC addition, rising from 58.6 MPa√m for the base alloy to a maximum of 68.5 MPa√m. SEM analysis of the fabricated samples revealed a uniform distribution of TiC within the Ti-6Al-4V matrix, and EDS elemental mapping confirmed the presence of Ti, Al, V, and C, with minor traces of O, N, and Fe. Tensile fracture surfaces showed ductile dimple fracture for the base alloy, whereas TiC-reinforced composites exhibited finer dimples and mixed-mode fracture behavior. Fatigue crack growth analysis using CT specimens indicated restricted crack propagation in reinforced samples. Fatigue strength was enhanced with the addition of TiC, with endurance strength increasing by 15.2%. S–N curves developed for different composites confirmed an improvement in fatigue life.