The effect of constituent phases on microstructure and high temperature deformation mechanisms of IrRhRuWMo complex concentrated alloys

The alloys with different primary phases (BCC, BCC + HCP, HCP, FCC) were fabricated using the same alloying elements: Ir, Rh, Ru, W, and Mo. Comprehensive microstructure characterization and phase identification were performed to reveal all existing phases present within the selected alloys. In situ strain jump compression test was carried out to assess mechanical properties and explore underlying deformation mechanisms, both at room temperature (RT) and 1500 °C. While a noticeable discrepancy in 0.2 % proof stress was observed among the selected alloys at RT, the difference was significantly minimized at 1500 °C. Furthermore, while the dual-phase structure effectively increased the 0.2 % proof stress at RT, it had a detrimental effect at 1500 °C. All alloys obeyed the power-law relationship both at RT and 1500 °C, exhibiting relatively high stress exponents. Together with calculated activation volume, these findings suggested that different rate-limited deformation mechanisms were likely activated at RT and 1500 °C. • The alloys with different primary phases (BCC, BCC + HCP, HCP, FCC) were successfully fabricated using Ir, Rh, Ru, W, and Mo. • While BCC alloy and BCC + HCP alloys displayed brittle characteristics, HCP and FCC alloys demonstrated a ductile nature. • All alloys obeyed the power-law relationship at both room temperature (RT) and 1500 °C. • Activation volume suggested two different rate-controlled mechanisms were individually activated at RT and 1500 °C.