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In this study, the role of a scan strategy in the fabrication of a single crystal (SX) structure of face-centered cubic (fcc) pure Ni using a flat-top laser profile by a laser powder bed fusion (LPBF) process was investigated. A flat-top laser with a uniform heat intensity across the beam profile was employed to fabricate the SX structure with a <001> texture parallel to the build direction (║BD). A meander scan strategy with an XY–90° scan rotation was required to achieve the flat-top-derived SX structure. The meander scanning strategy promoted the epitaxial <001> fcc growth along the direction ║BD, leading to the <001>║BD texture formation. Meanwhile, the XY–90° scan rotation induced the epitaxial growth of <001> fcc phase on the hatch direction (HD)–scan direction (SD) plane in the direction deviated by approximately 45° relative to the SD. This 45° deviation relative to the SD occurred to accommodate the beam movement and the circular beam geometry on the HD – SD plane, resulting in the preferred configurations of <011>║SD and HD. Thus, this paper reports the importance of meander scanning with a 90° scan-rotation strategy to yield a flat-top-LPBF-derived SX structure with <001>║BD and <011>║SD and HD textures. [ABSTRACT FROM AUTHOR]

The Fe50(CoCrMnNi)50 medium-entropy alloy can be considered a bridging alloy between the multicomponent medium- and high-entropy alloys and conventional steels. In this study, the combined effect of friction stir processing (FSP) and addition of WC-rich particles on the microstructure and mechanical properties of Fe50(CoCrMnNi)50 was investigated. The parameters of tool rotation speed and stir speed of the FSP were fixed at 400 rpm and 0.3 mm/s, respectively. In the stir zone, formation of ultrafine grains was observed, owing to the interrelated combination of dynamic recrystallization by the FSP, particle-stimulated nucleation, and grain-coarsening inhibition by the WC-rich particles. The combined utilization of FSP and WC-rich particles significantly improved the mechanical properties of Fe50(CoCrMnNi)50, owing to the Hall–Petch grain boundary and particle hardening. [ABSTRACT FROM AUTHOR]