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Materials science and engineering / A 872, 144946 - (2023). doi:10.1016/j.msea.2023.144946, In this work, high energy synchrotron X-ray diffraction was used during tensile testing of an as-cast eutectic AlCoCrFeNi2.1 high entropy alloy. Aside, from determining for the first time the volume fractions of existing phases, we further detail their role on the alloy deformation behavior. The two major phases, a soft disordered FCC and a hard ordered B2 BCC, were observed to exhibit a stress partitioning effect which can be used to modulate the mechanical response of the material based on the relative volume fraction of each phase. Dislocation density analysis revealed that the soft FCC phase had a significantly higher dislocation density right after the onset of plastic deformation. This is attributed to the existence of strain gradients across the lamellar structure, where the hard B2 BCC prevents free deformation of the FCC phase. Nonetheless, despite the increase of the dislocation density in the soft FCC phase, calculations of the strengthening effects induced by generation of dislocations are more significant in the hard B2 BCC phases, as this phase is primarily responsible for the strength increase in the alloy. Besides, the evolutions in dislocation density of the soft FCC and hard B2 BCC phases during tensile deformation obtained from synchrotron X-ray diffraction data are consistent with the evolution of KAM determined by EBSD characterization. Also, lattice strain analysis across two principal directions (parallel and perpendicular to the loading axis) reveals that for these specific orientations there is a preferential deformation of the hard FCC planes which can be related to the deformation response of specific lattice planes at distinct orientations, as well as to the phase partitioning stress behavior., Published by Elsevier, Amsterdam

Scripta materialia 222, 115053 (2023). doi:10.1016/j.scriptamat.2022.115053, filler wire. Electron backscatter diffraction and synchrotron X-ray diffraction were used to determine themicrostructural evolution, while microhardness mapping and non-contact digital image correlation wereemployed to assess the local mechanical response across the welded joints. Further, thermodynamic calculationswere implemented to support the understanding of the microstructure evolution. Through a systematic analysisof the microstructure evolution and mechanical properties, it is established a correlation between weldingprocess, microstructure and mechanical properties. Besides, this work lays the foundations for the use of low-costarc-based welding technologies for successful joining and application of welded joints based on high entropyalloys., Published by Elsevier Science, Amsterdam [u.a.]

A strategy to improve the tensile properties of Co17.5Cr12.5Fe55Ni10Mo5 (at%) medium-entropy alloy through high-pressure torsion and subsequent annealing is presented in this work. Microstructural study revealed that the high-pressure torsion process led to the formation of fine grains (≤~1 μm) and profuse nano-scale Mo-rich μ-phase precipitates. And resultantly, the yield strength of the alloy was tuned from ~400 MPa to ~1 GPa, while preserving reasonable uniform elongation over 15%. The combination of strengthening from grain refinement and precipitation contributed to the excellent strength, while the post-HPT annealing provided substantial ductility.

We investigated the stretch-flangeability of CoCrFeMnNi high-entropy alloy (HEA) in comparison with other face-centered cubic alloys (304 stainless steel and twinning-induced plasticity steel). The hole expansion ratio of the HEA was superior to those of the other alloys, attributed to fewer vulnerable sites for crack-initiation and the resulting high crack-resistance.