Mechanical properties and corrosion behavior in molten zinc of Mo–ZrO2 alloys

Abstract

The effect of the ZrO2 doping amounts on the corrosion properties and mechanical properties of the molybdenum alloys in molten zinc was investigated. Among them, the Mo-1.5 wt% ZrO2 alloy has good corrosion resistance (at 460 °C) and excellent mechanical properties. Compared with that of pure molybdenum, the tensile strength of the Mo-1.5 wt%ZrO2 increased by 16.69% in the rotary forged state and 58.26% in the 1200 °C annealed states, and the compressive strength increased by 16.53% and 84.46%, respectively. At a corrosion temperature of 460 °C, a MoZn7 corrosion layer was formed, which isolates the molybdenum matrix from direct contact with the molten zinc. The distribution of ZrO2 particles in the corrosion layer, which changes the diffusion path of zinc and molybdenum atoms, thus slowing down the corrosion process. The thickness of the corrosion layer gradually decreases with increasing doping amount, where the corrosion layer thickness of the Mo-2.0 wt% ZrO2 is 45.21% lower than that of the pure molybdenum. At a corrosion temperature of 560 °C, the molybdenum matrix is exposed to molten zinc and the grains peel off. As the bond between Mo grains is better than the bond between Mo grains and zirconia, the grain spalling of the zirconia-doped molybdenum alloys is severer than that of pure molybdenum.