Isothermal corrosion (γ′+γ) Ni3Al alloy in liquid zinc
(1.State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing, Beijing 100083, China2.北京市北京科技大学新金属材料国家重点实验室)
Abstract: 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 ℃ 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.
Key words: Ni3Al alloy; liquid zinc corrosion; hot-dip galvanizing; intermetallics