Abstract: Process for producing novel nickel superalloy bodies having increased resistance of to oxidation and corrosion at high temperatures. The process comprises applying a thin layer of a platinum-group metal and heating to an elevated temperature to diffuse or integrate the platinum-group metal into the surface of the metal superalloy. Then the superalloy body is packed into a container filled with a diffusion powder composition containing sources of aluminum and chromium metals and heated in a hydrogen gas atmosphere to an elevated temperature to codeposit and diffuse aluminum and chromium into the platinum-group metal-treated surface. Finally, the superalloy body is removed from the diffusion coating container and heated to the solvus temperature to form a ductile surface having an outer zone microstructure comprising a normally brittle PtAl.sub.2 which has been ductilized by the solutioning therein of beta chromium. This ductilized PtAl.sub.

Abstract: Improved powder-type diffusion-coating compositions for use in codeposition processes involving the formation of diffusion coating of chromium and aluminum on high nickel and high cobalt alloys known as superalloys. The compositions are characterized by easy flowability and, particularly, by the use of the intermetallic compound Co.sub.2 Al.sub.9.