Preparing of NiAl and Ni3Al Intermetallic Composite Coatings by Laser Cladding In Situ Synthesis
Ni-Al intermetallic compound coatings no visible cracks, pores or inclusions are prepared on mild steel substrate by Laser- cladding in situ synthesis with mixed powders of nickel-coated aluminum, Ni-based alloy and Al. The results show that the microstructure of the coating consists mainly of two phases of NiAl and Ni3Al, and the former amount is more than the latter, with NiAl being uniformity and staggered fine dendrites which are surrounded continuously by Ni3Al, and the atom ratios of Ni∶Al∶Fe∶Si in NiAl and Ni3Al are respectively 54∶39∶2∶5 and 70∶21∶3∶6. Compared with cladding nickel-coated aluminum, the coatings quality are improved, and the dilution of iron from substrate into coating are greatly reduced, as a result of lower cladding powers due to self-fluxing of Ni-based alloy and exothermic reaction between Ni and Al. The hardness of coatings are up to HV490-HV540.
Zhong Cao, Xueqiang Cao, Lixian Sun, Yinghe He
G. P. Cheng and Y. Z. He, "Preparing of NiAl and Ni3Al Intermetallic Composite Coatings by Laser Cladding In Situ Synthesis", Advanced Materials Research, Vols. 239-242, pp. 636-641, 2011