Isothermal corrosion (γ′+γ) Ni₃Al alloy in liquid zinc

The isothermal corrosion testing and microscopic examination of Ni₃Al alloy in liquid zinc containing small amounts of aluminum (mass fraction less than 0.2%) at 450°C were carried out. The results show that the controlling mechanism of the dissolution reaction is diffusion through a boundary layer into liquid zinc. For two-phase alloy, Ni₃Al alloy (γ′+γ), the interface between dissolving solid and liquid remains remarkably planar and the difference in dissolution of the two adjacent phases (γ′+γ) can not be experimentally observed. The boundaries between γ′ phase and γ phase play no perceptible role in the dissolution of Ni₃Al alloy in liquid zinc. The X-ray diffraction spectra of the diffusion layer confirm the presence of Ni₅Zn₂₁. The corrosion rate of the Ni₃Al alloy in molten zinc was calculated to be approximately 2.6 × 10^-3 g/(cm²·h), therefore the liquid zinc corrosion resistance of Ni₃Al alloy is very weak.