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A heterostructuring strategy is an effective approach for abiding problems referred to as the strength-ductility trade-off. However, tailoring the heterostructure is an arduous problem. This work synthesized hierarchically heterogeneity by combining the eutectic high-entropy alloy (EHEA) and medium-entropy alloy powders through novel powder metallurgy-based severe plastic deformation (P-SPD). EHEA forms nano-scaled heterogeneity composed of FCC and B2, and the mixture of powder types forms micro-scale heterogeneity with hard and soft domains. This hierarchically heterogeneous microstructure leads to strong hetero-deformation-induced strengthening, achieving a yield strength of ∼1.5 GPa. The present P-SPD represents the feasibility of heterostructuring, aiding the development of HEAs. A hierarchically heterogeneous microstructure comprised of the eutectic high-entropy alloy and medium-entropy alloy was synthesized by the P-SPD procedures and achieved supreme mechanical properties attributed by hetero-deformation-induced strengthening. [ABSTRACT FROM AUTHOR]

Thin-wall structures are promising for lightweighting with widened applications in topology-optimized lattice structures. Also, they are extensively used in heat exchangers because of their rapid heat transfer rate. This work presents the effects of thin-wall thickness on the microstructures, property, and anisotropy of the laser-powder bed fusion processed thin-walled structures with varied wall thicknesses of 0.3 mm, 0.5 mm, 1.0 mm, and 1.5 mm. The epitaxial columnar growth is favored, and the columnar grain aspect ratio increases with the wall thickness. Further, the columnar grain size increases and the geometrically necessary dislocation density decreases with increasing thickness. These microstructural differences significantly affected the tensile properties; the yield and the tensile strengths reduced, and the elongation increased with the wall thickness increase. Further, the L-PBF processed thin walls presented anisotropic properties. The samples tested along the build direction showed lower strength than those across the build direction. Moreover, the drop in strength with increasing thickness is less in the samples taken across the build direction than that along the build direction. Importantly, the degree of anisotropy increased with increasing wall thickness. [ABSTRACT FROM AUTHOR]

Developing metal additive manufactured (AM) parts with excellent mechanical properties broaden the utilization of AM parts in various industrial applications. Recently, gradient structures have received significant attention owing to their excellent mechanical properties. In this study, we propose a new strategy to obtain a superior gradient structure using annealing and ultrasonic nanocrystal surface modification (UNSM) on laser powder bed fusion (LPBF) fabricated 316 L stainless steel. The post-LPBF annealing treatment disturbed the cellular dislocation structure, which led to the optimized materials for gradient structure. The resulting gradient structure after the UNSM treatment has a thicker gradient layer with a significant strain partitioning between the domains than the LPBF followed by UNSM without annealing. As a result, the present LPBF-annealing-UNSM alloys show superior strength-ductility synergy compared to the LPBF-UNSM samples. [Display omitted] [ABSTRACT FROM AUTHOR]