Processes for protecting refractory metallic components against corrosion

In a process of forming a coating selected from nickel and cobalt-based coatings on a surface of a component comprising a metallic refractory material comprising at least 50% by weight of metal selected from the group consisting of iron, cobalt and nickel, the improvement comprising, forming chemically at least one layer comprising an alloy of boron with a member selected from the group consisting of nickel, cobalt and nickel/cobalt on the component, said layer being deposited by immersing the surface of the component in an aqueous bath containing at least one boron salt and at least one salt selected from nickel salts and cobalt salts, after which the boron is eliminated from the layer by heating the coated component in a halogenated and hydrogenated atmosphere at a temperature between 800.degree. and 1250.degree. C, the elimination of the boron being accompanied by diffusion of at least one of cobalt and nickel into the metallic refractory material.