Laser surface alloying of cast aluminium alloy with Ni and Cr

Ni-Cr powder was mixed into paste with a organic binding agent and then painted onto the surface of cast aluminium alloy ZL108 for laser surface alloying using CO2 laser.With optimum process parameters,the allo yed layer with good metallurgical bonding performance is formed.The microstructu re characteristics of alloyed layer are investigated by using OM,SEM,EDAX and XRD.The results show that the alloyed layer is composed of inter-metallic compo unds of Ni-Al,which is some particles dispersed on the substrate of Al-Si mut ual crystal.The micro-hardness of alloyed layer can reach up to 230HV,which was three times higher than that of the substrate materials.The relative wear resi stance is about two times higher than that of the substrate materials.