Cavitation erosion resistance of Ti6Al4V laser alloyed with TiC-reinforced dual phase intermetallic matrix composites

Austenitic NiTi (B2)/α2-Ti3Al multiphase TiC reinforced intermetallic matrix composites (IMC) were laser alloyed on Ti–6Al–4V using Ni/Al–TiC and Ni/Al–VC powder mixtures. The coatings were characterised by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and energy-dispersive spectroscopy (EDS). The laser alloyed layer using Ni/Al–TiC exhibited few surface cracks that were successfully eliminated by replacing TiC with VC in the starting powder mixture. Under vibratory cavitation conditions, the coatings exhibited a factor of 1.2–1.8 increase in erosion resistance compared to that of the base material. The influence of hardness of laser alloyed layers and work hardening ability of base material on erosion resistance was discussed. The co-existence of cavitation erosion resistant intermetallics in a carbide reinforced matrix was responsible for the improved erosion resistance. Based on the SEM surface micrographs of the eroded specimens, the failure mode of the alloyed layers was characterised as brittle fracture.