Interface morphology and corrosion behavior of bulk Fe2B in liquid Al

Abstract The corrosion behavior and products of bulk Fe 2 B in liquid Al at 750 °C were systematically investigated by static immersion tests, and characterized in detail through the joint approach of scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), electron probe micro-analyzer (EPMA), and transmission electron microscopy (TEM). The results indicate that the corrosion of Fe 2 B intermetallic in liquid Al is a diffusion-controlled process which involves the inter-diffusion of Fe and Al atoms at the solid-Fe 2 B/liquid-Al interface along with the formation of FeAl 3 intermetallics. The reactions between Fe 2 B and liquid Al results in a zigzag Fe 2 B/FeB two-phase transition region and a thick FeAl 3 intermetallic layer. The corrosion resistance of Fe 2 B against liquid Al can be attributed to the competition between the Fe 2 B/FeB phase transition, while the eventual corrosion results from micro-cracks developed from interfacial misfit, which enables spalling of the FeB and subsequent rapid corrosion of the matrix.