Ultra-high-temperature deformation of polycrystalline and directionally solidified L1₂ intermetallic compound Ir₃Nb

The ultra-high-temperature deformation behaviors of polycrystalline (PC) and directionally solidified (DS) L1₂ intermetallic compound Ir₃Nb have been investigated. The compression and compressive creep experiments were performed at temperatures from 1650 to 1800 °C at initial applied stresses from 49 to 200 MPa. The results show that the DS alloy has higher creep resistance and longer creep life than the PC alloy under above experimental conditions. The steady-state creep behavior of the DS alloy can be described in terms of power-law creep with the apparent stress exponent of 2.3 and activation energy of 295 kJ/mol. The creep mechanism is discussed in the light of the creep microstructure.