Microstructure and high-temperature mechanical properties of near net shaped Ti−45Al−7Nb−0.3W alloy by hot isostatic pressing process

• Published in: Transactions of Nonferrous Metals Society of China Vol. 30; no. 11; pp. 3006 - 3015
• Main Authors: LI, Hui-zhong, CHE, Yi-xuan, LIANG, Xiao-peng, TAO, Hui, ZHANG, Qiang, CHEN, Fei-hu, HAN, Shuo, LIU, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2020
• Subjects: high-temperature mechanical properties; near net shape; powder metallurgy; TiAl alloy; powder metallurgy; high-temperature mechanical properties; near net shape; TiAl alloy
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(20)65438-3

Near net shaped Ti−45Al−7Nb−0.3W alloy (at.%) parts were manufactured by hot isostatic pressing (HIP). The microstructure and high-temperature mechanical properties of the alloy were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that at a temperature of 700 °C, the peak yield stress (YS) and ultimate tensile stress (UTS) of alloy are 534 and 575 MPa, respectively, and the alloy shows satisfactory comprehensive mechanical properties at 850 °C. The alloy exhibits superplastic characteristics at 1000 °C with an initial strain rate of 5×10−5 s−1. When the tensile temperature is below 750 °C, the deformation mechanisms are dislocation movements and mechanical twinning. Increasing the tensile temperature above 800 °C, grain boundary sliding and grain rotation occur more frequently due to the accumulation of dislocations at grain boundary.