Effect of Hybrid Reinforcements and TiB Whisker Formation on the Mechanical Performance of Titanium Matrix Composites: An Experimental and Numerical Study

Abstract

This study investigates the fabrication and mechanical performance of titanium matrix hybrid composites (TMHCs) reinforced with boron carbide (B4C) and graphene (Gr) fabricated via the powder metallurgy (PM) method. Initially, Ti-xB(4)C composites with varying B4C contents (x = 1-10 wt.%) were produced to identify the optimum reinforcement ratio. The Ti-3B(4)C composition exhibited superior compressive strength (1230 MPa) and microhardness (313 HV) and was therefore 3 wt.% B4C selected as the reinforcement ratio for the subsequent hybrid composite process. To further enhance the mechanical properties, graphene was incorporated in varying amounts (y = 0.2-0.6 wt.%) to form Ti-3B(4)C-yGr hybrid composites. Among these, the Ti-3B(4)C-0.2Gr sample demonstrated the highest sintered density and compressive strength (1088 MPa), highlighting the effectiveness of synergistic reinforcement. Microstructural analyses via scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the in situ formation of TiB and TiC phases, which significantly contributed to the observed strengthening. However, increasing the graphene content beyond the optimal threshold led to agglomeration and excessive TiC formation, which adversely affected the mechanical performance. Furthermore, a finite element modelling (FEM) approach was employed to elucidate the mechanical contributions of in situ TiB whisker formation within the titanium matrix. The simulation results provided more profound insight into the reinforcing mechanisms and their role in enhancing the load-bearing capacity of composites. FEM provided valuable insights into the impact of TiB whisker formation on the compressive performance of the titanium matrix composite.