Formation of Mo(Si, Al)2 layer on Mo dipped in Al melt saturated with Si and the effects of transition metals added in the melt

Dipping Mo into Al liquid with saturated Si, a dense Mo(Si, Al)2 layer was formed on the Mo surface. Microstructure observation and chemical composition analysis of the Mo(Si, Al)2 layer reveal that the intermetallic layer consists of needle-like grains with diameter of submicrons and Al–Si liquid at their grain boundaries. Mo(Si, Al)2 grains are grown by the dissolution-precipitation process in the Al(Si) liquid located between Mo(Si, Al)2 and Mo. The product layers at the corners of Mo had radial cracks because the Mo(Si, Al)2 layer generated at the interface between the Mo(Si, Al)2 layer and Mo. Addition of Cr into the Al–Si liquid bath can prevent the formation of radial cracks.