Effect of Parameters of Mechanical Milling on the Formation of NiAl Coatings on the Nickel-Based Superalloy (Inconel 617)

In this study, mechanical milling has been applied to fabricate Ni-Al coating on the surface of a nickel-based superalloy (Inconel 617). In order to form the coating layer, Al powders accompanying the substrate (Inconel 617) and balls with different ball size and ball-to-powder weight ratio were placed and then ball milling was done for 5, 10, 15, and 20 h. During the mechanical milling process, due to the cold welding between powder particles and surface of substrate, coating layer was formed. . To form the intermetallic compositions, all samples were annealed at 550 °C for 120 min. In additions, to optimize of thickness and coating hardness the ball-to-powder weight ratio, milling duration, and ball size as effective parameters were investigated. The microstructure studies of samples was investigated by using of scanning electron microscopy (SEM).The results showed that the formation of Ni-Al intermetallic coatings on nickel-based superalloy (Inconel 617) have been formed. Also, the best coating was formed in milling duration of 15 h and ball to powder weight ratio of 10:1 and mixing ball 8, 12, and 16 mm diameter. Also, the maximum hardness of the formed coatings reached 1270 HV for sample ball milled for 15 hr.