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To fulfill the growing demand for alternative and sustainable feedstock production for metal additive manufacturing, a novel dual-stage ball milling strategy was proposed to effectively convert recycled stainless-steel machining chips to powder with desirable characteristics for metal additive manufacturing. A theoretical analysis was performed to evaluate the impact of ball size on the chips-to-powder evolution and the consequent powder morphology. To verify the viability of using the ball milled powder created from machining chips in metal additive manufacturing, single tracks have been successfully deposited via laser engineered net shaping deposition and compared to the single tracks made from gas atomized powder using identical deposition conditions. The microstructures of these single tracks exhibited adequate adhesion to the substrate, a uniform melt pool geometry, continuity, and minimal splatter. Minimal differences in grain structure were observed between the single tracks made from ball milled powder and those made from gas atomized powder.

The present work investigated the viability of using nanometric 3 mol% yttria partially stabilized zirconia (3YSZ) as a particulate reinforcement in ultrafine grained aluminum alloy matrix composites. Four types of composite materials, with variable amounts of coarse grain regions and volume fractions of 3YSZ, were fabricated through cryomilling and hot isostatic pressing; one of the materials was extruded. Al–Mg alloy (AA5083) was selected as the matrix alloy. Microstructural characterization revealed that the 3YSZ particles were well dispersed in the Al matrix. The grain sizes of the Al matrix ranged from 77 ± 41 to 362 ± 185 nm depending on the thermomechanical processing. The composite with 2.2 vol% 3YSZ exhibited an ultimate tensile strength of 795 MPa and a strain-to-failure of 1.84%. In contrast, the composite with 10 vol% 3YSZ exhibited an ultimate compressive strength of 611 MPa with 22.5% strain-to-failure; this composite also retained 30% of its room temperature strength at 673 K (400 ℃). Evaluation of strengthening mechanisms suggests that Hall-Petch strengthening is a predominant mechanism controlling the achieved strength.