Surface electropulsing-induced texture evolution in electron beam melted Ti-6Al-4V alloy for biomedical application

Abstract

Surface electropulsing treatment has been demonstrated to significantly improve the surface strength of electron beam melted (EBM) Ti-6Al-4V alloy. However, further investigation is needed to understand the effect of this treatment on the surface texture of the alloy, as the texture of Ti alloy plays a crucial role in its corrosion performance. In this study, we explored the changes in texture induced by surface electropulsing in EBM Ti-6Al-4V alloy using electron backscattered diffraction (EBSD) and micro-region X-ray diffraction (Micro-XRD). The results revealed that surface electropulsing created a 〈0001〉α′//transverse direction (TD) texture on the alloy surface, and the intensity of this texture remained unaffected with varying electropulsing time (180–240 ms). Additionally, this treatment led to the formation of long curved martensite laths that could cross the small angle prior-β grain boundaries. The finite element method (FEM) was employed to aid in the analysis of the texture evolution mechanism. The results revealed that the most rapid cooling rate occurred perpendicular to the contact surface with the copper electrode, along the building direction (BD). When the (0001) plane aligned parallel to the direction of the fastest cooling rate, it promoted the growth of martensite, leading to an increased production of martensite with the (0001) plane parallel to the BD direction and generating the 〈0001〉α′//TD texture. Therefore, by controlling the position of the copper electrode during surface electropulsing treatment, it is possible to manipulate the orientation of the (0001) plane of most α′ laths. This suggests that surface electropulsing treatment holds potential for application in other Ti alloys to enhance strength and optimize texture for biomedical applications.