Effect of applied stress on creep behavior and microstructure evolution of Mo–3Nb single crystal at high temperature

The high-temperature creep behavior and microstructural evolution of Mo–3Nb single-crystal was investigated under applied stresses ranging from 30 to 70 MPa at 1650 °C. The creep test results show that the creep rate of Mo–3Nb single crystal increased from 5.5 × 10⁻⁵ s⁻¹ (30 MPa) to 2.2 × 10⁻² s⁻¹ (70 MPa). The microstructure evolution of Mo–3Nb single crystals after creep deformation was characterized by electron backscatter diffraction and transmission electron microscopy. With the increase of applied stress, low-angle grain boundaries transferred to equiaxed polycrystals during the creep deformation, and the complete recrystallization occurred at a stress of 70 MPa. TEM analysis shows that the creep behavior of Mo–3Nb single crystal is dominated by dislocation slip under 30 MPa, while the creep mechanism transforms into diffusion creep under 70 MPa, which is attributed to the generation of dynamic recrystallization. This study provides important theoretical insight for understanding the high-temperature creep behavior of Mo–3Nb single crystals, offering a basis for the design of creep-resistant materials.