Study of Ag precipitation and mechanical properties of Ti–Ta–Ag ternary alloy

Abstract

Ti–25Ta–xAg alloy samples with different content of Ag were prepared by spark plasma sintering method. X-ray diffraction, microscopic metallographic, scanning electron microscopy, and transmission electron microscopy were used to analyze the phase structure and morphology of the alloy samples. Ti–Ta–Ag can form a stable ternary alloy system. Furthermore, with the increase of Ag content and sintering temperature, Ag will be precipitated at the grain boundary. In order to explore the precipitation mechanism of Ag in the alloy and its influence on the mechanical properties, the crystal structure, electronic structure, and elastic constant under different Ag solid solubility were calculated systematically by using first-principles calculations. The results show that the critical temperature of Ag in Ti–Ta–Ag ternary alloy is about 2200 K, and the high temperature is favorable for the aging precipitation of Ag. The lattice constants and mechanical properties of (Ti_1−xAg_x)₃Ta solid solution suddenly change when the Ag solid solubility x value is equal to 0.8, and their changes will follow different rules. The internal mechanism of this phenomenon is that the 4d¹⁰ electronic states of Ag have changed from obvious local electronic states to mixed local and non-local electronic states. These results provide theoretical guidance for the application of Ti–Ta–Ag ternary alloys in biomedicine.