Deformation behavior and microstructure evolution of as-cast Ti2ZrMo0.5Nb0.5 high entropy alloy

Abstract

A high entropy alloy (HEA) with a composition of Ti2ZrMo0.5Nb0.5 was prepared by vacuum induction melting technology. The mechanical properties at room temperature and elevated temperature (900 °C–1150 °C), microstructure evolution and hot deformation behavior during hot deformation are studied. The as-cast alloy is composed of equiaxed grains with the yield strength, the apparent plastic strain of 1306 MPa and 44%, respectively. By TEM analysis, the ZrTi2 Laves C15 phase is found corresponding the precipitation strengthening effect accompanied with the solid solution strengthening as a ramification of the high-entropy alloy. Then the hot compression tests were carried out. The deformed alloy still maintains the same single BCC structure as the as-cast state. It is noted that when the temperature is 900 °C, the structure of the alloy mainly exhibits dynamic recovery (DRV) characteristics, and when the temperature reaches 1000 °C, there are clear dynamic recrystallization (DRX) characteristics in the structure, which are analyzed as the features of continuous dynamic recrystallization (CDRX). Keeping the temperature at 1150 °C, when the strain rate is 0.1 s−1, the characteristics of discontinuous dynamic recrystallization (DDRX) appear, and as the strain rate decreases, CDRX becomes the main recrystallization mechanism again.

Keywords

• Ti2ZrMo0.5Nb0.5 high entropy alloy
• Hot deformation
• Dynamic recrystallization
• Microstructure evolution