The corrosion of intermetallic alloys in liquid zinc

We studied the static isothermal corrosion of three intermetallic alloys: Fe3Si, Fe3Al and Ni3Al alloy in liquid zinc at 450 °C compared with 316 stainless steel in this paper. The three intermetallic alloys showed a lower resistance to corrosion than 316 stainless steel in liquid zinc. The intermetallics exhibited one or two regular corrosion layers, and the corrosion process was controlled by the dissolution mechanism in liquid zinc although the respective corrosion processes were different. There was no preferential corrosion. The respective corrosion processes were discussed below.An aluminum-rich layer was formed on the surface of 316 stainless steel and Fe3Si alloy, and acted as a diffusion barrier to zinc, while aluminum itself did not diffuse into the solid matrix. The elements of solid matrix (316 stainless steel and Fe3Si alloy) diffused through the aluminum-rich layer into liquid zinc. Chromium in Fe3Al alloy and 316 stainless steel dissolved preferentially from the corrosion layer into liquid zinc. Silicon dissolved preferentially from Fe3Si alloy matrix into the corrosion layer. The interface between the solid Ni3Al alloy and liquid zinc remained almost smooth and was independent of microstructure. The boundaries between solid phases (γ and γ′) played no perceptible role in the dissolution of Ni3Al alloy.