Mechanical and microstructural responses in molybdenum-rhenium alloys under hot compressions

To study temperature and rate-dependent behaviors of molybdenum-rhenium (Mo-Re) alloys, compressive tests at variable temperatures and strain rates were conducted. After the same machining and thermal annealing processes, fully recrystallization happens in Mo and Mo-Re alloys with low Re content (5 wt. %), while recovery occurs in Mo-Re alloys with high Re content (14 wt.% and 42 wt. %). The strength increases as Re content rises at all temperatures (300 °C, 600 °C and 1200 °C), meaning sufficient strengthening effect of Re. The rate-dependent behaviors, however, show different trends between Mo and Mo-Re alloys. Positive strain rate sensitivity is detected in Mo and low Re Mo-Re alloys in all temperatures, which is consistent to other research. While, near zero strain rate sensitivity is found in high Re Mo-Re alloys at 600 °C. Such an unusual phenomenon may be contributed to high stored dislocation density during mechanical processes. The stored dislocations are activated at a proper temperature to accommodate plastic flow, which weakens the influence of strain rate on strength.