Microstructures and mechanical properties of Ti–45Al–8.5Nb–(W,B,Y) alloy by SPS–HIP route

Microstructures and compression properties of Ti–45Al–8.5Nb–(W,B,Y) alloy consolidated by spark plasma sintering (SPS) and hot isostatic pressing (HIP) were investigated. The results showed that sintering temperature has a significant effect on microstructure. When the sintering temperature is 1000 °C, the dendritic microstructure of as-SPS alloy is similar to that of the alloying powder. At 1100 °C, the interfaces of these powder particles are still discernible, but near γ microstructure appear in every particle. A typical fully lamellar (FL) microstructure followed by two types of microsegregations, such as β-segregation and α-segregation, is successfully developed at 1200 °C. However, FL microstructure becomes coarser at 1300 °C. As-HIP alloy has near lamellar (NL) microstructure along with β-segregation. The morphologies of β phase in as-HIP alloy are different from those in as-SPS alloy. The alloy exhibits excellent compression properties at elevated temperatures. When compression temperature is higher than 1100 °C, high quality compressed samples without cracks can be obtained even if engineering compression strain is up to 80% for the strain rates of 1 × 10−1 to 10−3 S−1.