Electroshock treatment dependent microstructural evolution and mechanical properties of near-β titanium alloy manufactured by directed energy deposition

Effects of electroshock treatment (EST) on the microstructural evolution and mechanical properties of near-beta titanium alloy (Ti-55531) formed by directed energy deposition (DED) was studied in this work. With the increase in EST time, the average hardness of specimen decreased from 426 HV to 316 HV, and the fracture strain increased significantly, which was attributed to the uniform dispersion of alpha phase along grain boundaries and inside the beta grains. After EST, the texture intensity decreased in terms of the orientation distribution function (ODF), which was ascribed to the redistribution of alpha phase. Moreover, more atomic vacancies and lattice distortion were formed near the alpha/beta interfaces, which were verified by transmission electron microscopy (TEM) observation and ascribed to the migration of atoms near the interface under EST. External loadings facilitated the dislocation motion and lattice distortions near the interfaces, which resulted in the reduction in hardness and the improvement in ductility. The above results indicated that EST can quickly alter the microstructure and mechanical properties of DED titanium alloys as a simple and energy-saving method. (C) 2021 Published by Elsevier Ltd.