Effects of Laser Process Parameters on Melt Pool Thermodynamics, Surface Morphology and Residual Stress of Laser Powder Bed-Fused TiAl-Based Composites

A coupled discrete element method and computational fluid dynamics (DEM-CFD) approach was utilized to systematically investigate the mesoscale dynamics of single-track melt pools in laser powder bed fusion (LPBF) of TiAl-based composites. It was found that the melt pool’s temporal evolution and flow behavior are predominantly governed by recoil pressure and Marangoni convection. When lower laser power and higher scanning speeds are applied, the melt pool size is limited due to restricted energy input, resulting in increased cooling rates and steeper temperature gradients. Under these conditions, residual stresses are slightly elevated. However, crack initiation and propagation are partially suppressed by the refined microstructure formed during rapid cooling, unless a critical stress threshold is surpassed. In contrast, the use of higher laser power with lower scanning speeds leads to the formation of wider and deeper melt pools and an expanded heat-affected zone, where cooling rates and temperature gradients are reduced. Under these circumstances, significant recoil pressure induces interfacial instabilities and surface perturbations, thereby considerably increasing the likelihood of cracking. The reliability of the developed model was confirmed by the close agreement between the simulation results and experimental data.