The microstructural evolution and wear properties of Ni60/high-aluminum bronze composite coatings with directional structure

The directional structure of Ni60/high-aluminum bronze composite coating was formed using induction remelting and forced cooling. The microstructural evolution and the characteristics of interface growth were studied. The results showed that the remelted coating formed metallurgical bonding with the substrate. The microstructures changed from plane crystal to dendrite, cellular dendrite, fine cellular dendrite, and then to dendrite again with the increase in the cooling rate. The crystal grew along the heat flow direction and had (111) and (200) preferred orientations when the cooling rate was 1.886 ml·min −1 ·mm −2 . The plane crystal, dendrite and cellular dendrite were mainly composed of compounds and solid solutions with Ni, Fe and Cu, and they were surrounded by strengthening phases composed of Cr, C and B. The grain boundary of directional structure coatings showed the characteristic of regular eutectic growth, but grain boundary of remelted coating presented characteristic of divorced eutectic growth. The wear resistance of directional structure coatings is better than that of remelted coating.