Effect of Cu Particle Cross-Contamination in AlSi10Mg Powder Feedstock: Tensile and Strain-Hardening Behaviour of Multi-Material Laser Powder Bed Fusion Parts

Cross-contamination during metal powder blending in multi-material laser powder bed fusion (PBF-LB/M) is a common production challenge and a key barrier to the wider industrial adoption of the process. In the present investigation, the effect of different CuCr1Zr foreign-particle cross-contamination rates of up to 5.0 wt.%, simulating different cross-contamination levels in an AlSi10Mg feedstock for PBF-LB/M, is examined. The resulting metallurgical features and tensile mechanical properties of the produced components were compared to those of reference specimens manufactured from uncontaminated powder. A microstructural analysis of CuCr1Zr contaminated samples revealed characteristic Cu-rich regions, demonstrating that the higher the level of cross-contamination is, the larger these regions are. Tensile yield stress is almost linearly increased with the contamination level while the opposite trend is noticed for tensile elongation at fracture. Two different stages of strain-hardening were noticed, with Stage I exhibiting a lower strain-hardening exponent, while higher strain-hardening exponents (>0.27) were noticed for Stage II, with the latter decreasing with increasing cross-contamination level. The tensile mechanical behaviour of PBF-LB/M specimens was evaluated for the first time with appropriate quality indices, which were initially developed for similar cast aluminium alloys. Overall, the quality index accounting for global tensile performance was decreased for all build directions with increasing cross-contamination level. Despite the lower quality index at the non-contamination level, the inclined (45°) printed specimens presented quality indices that were almost unaffected by the cross-contamination level.