Microstructural and Wear Resistance Enhancement of Ti6Al4V Alloy via Oscillating Laser Deposition of WC Particles

Abstract

Additive manufacturing (AM) technologies are rapidly advancing, with Laser Directed Energy Deposition (L-DED) as a key application, frequently employing Gaussian lasers as the energy source. However, materials deposited via Gaussian laser deposition often exhibit significant temperature gradients and residual stresses, leading to defects such as cracking and deformation. In this study, Ti6Al4V and WC/Ti6Al4V alloys were fabricated using circular oscillation laser deposition and compared to those produced with Gaussian laser deposition. The research results indicate that the circular oscillation laser during deposition exhibits a stirring effect on the melt pool, suppressing the formation of elongated dendrites and promoting grain refinement. Under the impact of the high-energy laser beam, partial decomposition of WC into W and C leads to the formation of TiC and W₂C interface layers at the WC/matrix boundary, resulting in strong bonding properties. Additionally, uniformly distributed unmelted WC particles in the composite material effectively impede the growth of columnar dendrites. Compared to Ti6Al4V and WC/Ti6Al4V alloys produced via Gaussian laser deposition, specimens fabricated with circular oscillating laser deposition exhibited increases in microhardness of 9% and 6%, and reductions in wear rates of 22% and 77%, respectively. The Ti6Al4V composite containing 10 wt% WC prepared by Gaussian laser deposition exhibited exemplary corrosion resistance.

Graphical Abstract