Effect of minor boron addition on the fatigue strength and high temperature properties of injection molded Ti-6Al-4V compacts

Ti-6Al-4V alloy has attracted a lot of attention from the automotive and aerospace industries because of their outstanding specific strength and corrosion resistance. On the other hand, Ti-6Al-4V alloy has normally poor workability because of the low thermal conductivity and the low elastic modulus. Metal injection molding (MIM) process is expected to manufacture a complex part with near net shape and reduce the manufacturing cost. However, Ti-6Al-4V alloy compacts by MIM process had a problem of low fatigue strength compared to wrought material. In this study, we tried to add a minor amount of boron using TiB2 powder for improving the fatigue strength. Addition of boron resulted refinement of the grain size of lamellar structure, which lead to increase the high cycle fatigue strength and fatigue limit. In addition, tensile properties at high temperature was investigated.