Codeposition of Co and Al on nickel base superalloys by pack cementation process

►The thermochemical analyses were adopted for a series of pack powder mixtures. ►The codeposition of Co and Al could be obtained based on the thermochemical analyses. ►The outer layer of the coating was mainly composed of Al0.9Ni1.1 where a part of Ni was replaced by Co. ►The coating exhibited the excellent oxidation resistance due to the formation of protective α-Al2O3.