Effect of NbC on the microstructure and wear resistance of laser powder bed fusion (LPBF) processed AlSi10Mg alloy

AlSi10Mg- x (NbC) composites ( x = 0.1, 0.2, 0.5 wt. %) were fabricated via laser powder bed fusion (LPBF) using gas-atomized AlSi10Mg powder and submicron NbC particles in this work. Microstructural analysis reveals that minor NbC addition can refine the cellular subgrains of as-printed sample, reducing the average grain size from 1.0 μm to 0.5 μm (0.1 wt. % NbC addition). Concurrently, eutectic Si phase precipitates more continuously and densely along grain boundaries, elevating microhardness to 125 HV, a 60% increase over as-cast AlSi10Mg alloy. Tribological tests show optimal wear performance at 0.1 wt. % NbC addition, with a friction coefficient of 0.27 and wear rate of 1.44 × 10 -7 mm 3 /(N·m), representing 27% and 71% reductions, respectively, versus the as-cast counterpart. The enhanced wear resistance stems from a synergistic effect: grain refinement induces a grain boundary barrier that suppresses plastic deformation and abrasive ploughing, while the dense eutectic Si network and well-dispersed NbC particles jointly provide load-bearing and anti-wear capabilities. Excessive NbC (>0.5 wt.%) causes particle agglomeration, disrupting eutectic continuity and slightly degrading performance. This work demonstrates LPBF-enabled microstructural design as an effective route to high-performance, wear-resistant aluminum matrix composites.