Abstract
The behavior of Mo in contact with molten Al was modelled by classical molecular dynamics (CMD) simulation of a pure Mo solid in contact with molten Al at 1200 K using the Materials Studio®. Results showed that no reaction or cross diffusion of atoms occurs at the Mo(s)–Al(l) interface, and that molten Al atoms exhibit an epitaxial alignment with the exposed solid Mo crystal morphology. Furthermore, the two phases {Mo(s) and Al(l)} are predicted to interact with weak van der Waals forces and give interfacial energy of about 203 mJ/m2. Surface energy measurements by the sessile drop experiment using the van Oss–Chaudhury–Good (VCG) theory established a Mo(s)–Al(l) interface energy equivalent to 54 mJ/m2, which supports the weak van der Waals interaction. The corrosion resistance of a high purity (99.97%) Mo block was then tested in a molten alloy of 5% Mg mixed in Al (Al-5 wt.%Mg) at 1123 K for 96 h, using the ALCAN’s standard “immersion” test, and the results are presented. No Mo was found to be dissolved in the molten Al-Mg alloy. However, a 20% mass loss in the Mo block was due to intergranular corrosion scissoring the Mo block in the ALCAN test, but not as a result of the reaction of pure Mo with the molten Al-Mg alloy. It was observed that the Al-Mg alloy did not stick to the Mo block.
Highlights
Equipment failure caused by corrosion wear, which is accelerated by contact with molten aluminum and its alloys, is one of the main problems facing the Al industry [1].Various investigations into the resistance behavior of countless materials, including metals, Fe-based alloys, and their corresponding apparatus for high-temperature applications have been conducted for corrosion wear in molten Al and its alloys
Experimental data from the static ALCAN immersion test agree with the simulation results, some traces of Al-Mo alloys were detected on the Al-rich side of the Mo(s)–Al(l) interface
A weak interaction existed between the Al-Mo alloys and the solid Mo block (Mo-rich side), making it easy for Mo to peel off and demonstrate its anti-wetting properties; we suspect that the 20% mass loss on Mo was due to the chemical attack along the grain boundaries leading to intergranular corrosion
Summary
Equipment failure caused by corrosion wear, which is accelerated by contact with molten aluminum and its alloys, is one of the main problems facing the Al industry [1]. Various investigations into the resistance behavior of countless materials, including metals, Fe-based alloys, and their corresponding apparatus for high-temperature applications have been conducted for corrosion wear in molten Al and its alloys. Since Al has a tendency to stick to other metals, a coating of boron nitride, for example, is spray-painted to cover sow moulds in order to prevent the molten Al from sticking [2]. In the Al industry, which produces Al-Mg alloys, corrosion leads to contamination of the alloy products arising from the solid impurities that come from, for example, the sow molds, rotor material, or degraded refractories [4]
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