Microstructural Characterization of Ceramic-Reinforced Ti–6Al–4V Alloys using SEM, EDS Mapping, and EBSD Techniques

This study examines the improvements in microstructure and hardness of Ti-6Al-4V alloys reinforced with 5 wt% TiN and TiB₂. These ceramic reinforcements were incorporated through spark plasma sintering (SPS). Adding Cr and Ni significantly refines the β-phase microstructure and stabilizes its distribution. Meanwhile, TiN particles serve as effective nucleation sites, and the in situ TiB₂ whiskers help pin grain boundaries, promoting dynamic recrystallization. EBSD analysis shows a marked reduction in grain size, decreasing from 8.91 μm in the unreinforced alloy to 5.27 μm in the composite. This analysis also reveals a weak crystallographic texture and a predominance of low-angle grain boundaries, indicative of sub-grain formation. The combined effects of grain boundary refinement, dispersion strengthening from TiN and TiB₂ particles, and β-phase stabilization through the addition of Cr and Ni lead to a significant increase in hardness, rising from 353 HV_0.2 in the matrix alloy to 592 HV_0.2 in the composite.