Tensile properties of Mo-3Nb alloy rod at different strain rates

Abstract Owing to its intrinsic brittleness, the application of Mo as a structural material at room temperature is significantly limited. To enhance its mechanical properties under such conditions, Mo-3Nb alloy rods were fabricated via melting, extrusion and forging processes, and subsequently subjected to tensile tests at various strain rates. The results demonstrate that as the strain rate decreases, the tensile strength of the specimens declines, while their toughness improves. This behavior is primarily ascribed to the fact that at lower strain rates, dislocations have adequate time to bypass obstacles, thereby mitigating stress concentration and inhibiting the initiation of microcracks. Even if microcracks eventually form, the elongated grain structure of the rods facilitates crack deflection, which dissipates crack propagation energy. Specifically, at a strain rate of 1.67 × 10 −2 s −1 , the specimen exhibits a maximum strength of 772 MPa, but with an elongation of only 1%. In contrast, at a strain rate of 1.67 × 10 −4 s −1 , the specimen achieves an optimal combination of high strength and high toughness: a strength of 632 MPa, attributable to the solid-solution strengthening effect of Nb, and an elongation of 12.7%.