Nano-precipitation and tensile properties of Ti60 alloy after exposure at 550 °C and 650 °C

The precipitation behavior of the silicide in Ti60 alloys was studied after exposure treatments at 550 °C and 650 °C for 8 h, 50 h and 100 h, respectively. In addition to the boundary of the α plate, the dislocations and stacking faults can also be preferred as nucleation sites for the silicide in the alloy exposed at 650 °C for 50 h. The pinning effect of the silicide on dislocations was investigated by comparing the tensile properties and deformed microstructures at both room temperature and 150 °C. At room temperature, few slip bands and dislocations were observed in the deformed microstructure. Dislocations were observed around the boundary of the α plate after 100 h exposure at 550 °C, owing to the pinning effect of silicide. When the deformation temperature was raised to 150 °C, the density of slip bands and dislocations increased, and intersections of them were observed. Moreover, the pinning effect of the silicide appears to be weaker at higher tensile test at tensile testing temperatures. Accordingly, elongation of the alloy was less than 5% after exposure treatments at room temperature, but increased to above 20% at 150 °C.