Process for simultaneously aluminizing nickel-base and cobalt-base superalloys

A process for simultaneously forming diffusion aluminide coatings on surfaces of nickel-base and cobalt-base substrates, the process comprising the steps of:

• placing a nickel-base substrate and a cobalt-base substrate in a chamber;
• and then
• subjecting the nickel-base and cobalt-base substrates to a vapor phase deposition process performed at about 1900.degree. F. to about 1950.degree. F. for a duration of 4.5 to 5.5 hours in an inert or reducing atmosphere, the vapor phase deposition process using an aluminum-containing donor and an aluminum halide activator, the aluminum-containing donor containing about 50 to about 60 weight percent aluminum, the aluminum halide activator being aluminum fluoride present within the chamber in an amount of at least 1 gram per liter of chamber volume, the nickel-base and cobalt-base substrates developing diffusion aluminide coatings thereon, wherein the diffusion aluminide coatings that develop on the nickel-base and cobalt-base substrates have thicknesses that do not differ from each other by more than 30%.