Enhancement of laser energy absorption in high-reflectivity Cu-Cr-Zr alloy through laser powder bed fusion process optimisation using an interaction-term regression analytic method

The low laser energy absorption and unstable energy coupling in laser powder bed fusion (LPBF) of high-reflectivity alloys constrain the processing window and attainable part quality. This work investigates process-parameter effects on laser energy absorption for a high-reflectivity Cu-Cr-Zr alloy by integrating experiments with multiscale numerical simulations. An interaction-term regression model was established to apportion the relative contributions of each process parameter across segmented volumetric energy density (VED) intervals, using relative laser absorptivity measured via an integrating-sphere setup. The results exhibited that when the VED was below 12.5 J/mm³, reducing the scan speed was more effective for enhancing absorption. The benefits of raising the laser power continued to grow with increasing VED, being dominant between 12.5 J/mm³ and 25 J/mm³, but they tended to reach saturation at higher VED values. In contrast, the energy absorption showed limited sensitivity to powder layer-thickness increases. Accordingly, powder-bed ray-tracing simulations verified that absorption gains saturate once the layer-thickness exceeds 0.06 mm. Finally, complementary computational fluid dynamics simulations were conducted to discuss the effects of VED-regulated melt-pool regime transitions on effective laser absorptivity and printability. These results offer a feasible method for identifying critical levers and designing robust processing windows for LPBF of high-reflectivity alloys.