LAUSR

Abstract ZrO2/Mo alloy bars are fabricated by hydrothermal method and powder metallurgy process, with their microstructures, density, hardness, strength, reduction of area and elongation under ambient temperature investigated experimentally. The high temperature deformation stress of these alloy bars are tested through thermomechanical simulator. Results show that the second phase (ZrO2) in the microstructure was fine. As addition amount of the second phase increases, the microstructures of the matrix are refined, the density decreased while the hardness and strength are enhanced. Under high temperature, the second phase in ZrO2/Mo alloy bars can improve compressive stress of the alloy effectively by fine-grain strengthening and intra-granular and grain-boundary strengthening. At 1400 °C, the deformation stress of Mo alloy bars with 1.5% ZrO2 can be 20% higher than that of pure molybdenum. The strengthening effect of the second phase at high temperature are analyzed. The increase of strengthening effect is actually the manifestation of the pinning effect on hindering recrystallization behavior. It is shown that the improvement of mechanical properties of alloys at elevated temperatures should be mainly attributed to the retardation of recrystallization by the second phase.