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.