Effects of yttrium on mechanical properties and chemical stability of passive film of aluminide coating on 1045 steel

The effects of yttrium on the mechanical properties and chemical stability of passive film of an aluminide coating on 1045 steel were studied. The chemical composition of the coating was analyzed using energy-dispersive spectrometry (EDS). The scratch resistance of passive films on Y-free and Y-containing aluminide coatings was evaluated using a universal micro-tribometer. The mechanical properties of the passive films, as well as the coatings themselves, were investigated using a nano-mechanical probe. It was demonstrated that passive film on the Y-containing aluminide coating was harder and more elastic than that on the Y-free coating. Electron work function (EWF) measurements indicated that passive film on the Y-containing coating was more chemically stable than that on the Y-free coating. All tests demonstrated that yttrium was markedly beneficial to the aluminide coating. In particular, yttrium considerably improved the mechanical properties and the chemical stability of the passive film of the aluminide coating. Such improvement greatly benefits the aluminide coating against corrosion, corrosive wear and oxidation.