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The near-β Ti-55531 (Ti-5Al-5Mo-5V-3Cr-1Zr, wt%) alloy with thin-wall structures were manufactured by laser melting deposition (LMD), and followed by the post-processing of electroshocking treatment (EST). The microstructure evolution before and after EST were characterized via using the scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). The results showed that the microstructure of as-deposited specimen was mainly composed of short columnar grains and equiaxed grains, showing a unique structure of alternating short columnar grains-equiaxed grains-short columnar grains. The results of EBSD showed that EST could reduce the orientation concentration and weaken the texture of β phase. XRD results indicated that the α phase content slightly increased after EST. The micro-strain and lattice constant of β phase were changed after EST, which were probably ascribed to the precipitation of α, the generation of crystal defects on α/β interface, and the decrease of texture intensity. The results of mechanical properties indicated that EST could increase the microhardness, the yield strength and the tensile strength, which were due to the variation of microstructure. All results show that EST is an effective approach for optimizing the microstructure and improving the mechanical properties of LMD near-β titanium alloy. [Display omitted] • LMD Ti-55531 shows a unique structure of alternating columnar-equiaxed-columnar grains. • EST can alleviate the orientation concentration and weaken the texture of β phase. • More α tends to precipitate inside β after EST, due to the thermal and athermal effects of EST. • Variation of micro-strain and lattice constant are ascribed to the precipitation of α and decrease of texture intensity. • EST can optimize microstructure and improve mechanical properties of LMD near-β titanium alloy. [ABSTRACT FROM AUTHOR]

In this work, ultrasonic shot peening (USP) was performed for a CrMnFeCoNi high-entropy alloy with an equal atomic ratio to improve the mechanical performance at room temperature. The microstructure evolution and mechanical properties of the CrMnFeCoNi high-entropy alloy under different USP durations were studied. The effects of USP-induced grain refinement, phase transformation, strengthening, and fracture morphologies were analyzed. The results indicated that a certain thickness of compressive residual stress layer with nanocrystalline was formed on the surface of the alloy. After USP, the phase was transformed from the FCC phase to the mixed dual phases FCC+BCC. The alloy exhibited a strength-ductility balance, with hardness and strength enhanced significantly, while elongation to failure remained at around 30%. Additionally, the sample before USP exhibited a typical ductile fracture, while after USP, it was transformed into a mixed fracture of dimple and quasi-cleavage or cleavage. The crack initiated from the sub-surface rather than the initial surface, and then propagated to the interior structure after coming into contact with the surface strengthening layer, effectively delaying the failure of the material. It was demonstrated that the ultrasonic shot peening treatment is a general and efficient physical strengthening method for high-entropy alloy at room temperature. • Ultrasonic shot peening (USP) process was applied on the CrMnFeCoNi high-entropy alloy. • Surface grain refinement from the microscale to the nanoscale. • Phase transformation from the FCC phase to the mixed dual phases FCC+BCC. • The surface mechanical properties were improved and a strength–ductility balance was achieved after USP. [ABSTRACT FROM AUTHOR]