Surface modification

摘要

Properties of a surface layer of a metal part are modified by changing its composition and microstructure using focused radiant energy. Minor components of an alloy having the metal of the substrate as the major component thereof are applied to the surface and a limited depth surface layer of the substrate metal is melted, the coated-on components are mixed therewith and the mixture is rapidly cooled to produce a desired surfacing alloy to a controlled depth within the substrate and having a fine grained microstructure compared to the microstructure of the substrate metal. The amount of coated-on minor alloy components and the preselected depth of melting of the substrate metal provide alloy composition control. The melting is carried out by application of focused radiant energy using a laser, preferably applied in a manner to promote mixing of the coated-on minor alloy components and the molten substrate layer during the short time, on the order of tenths of a second, of molten state maintenance for any given surface area.