Abstract: In some examples, an article including a substrate and a multi-layered coating on at least a portion of the substrate. The multi-layered coating including at least one nano-crystalline layer comprising a metal or a metal alloy and a corrosion resistant layer on the at least one nano-crystalline layer. The nano-crystalline layer defining an average grain size of less than 50 nanometers (nm) and the corrosion resistant layer including at least one of nickel metal, tin metal, zinc metal, cadmium metal, chromium metal, nickel-phosphorus alloy, nickel-sulfur alloy, nickel-boron alloy, nickel-cadmium alloy, nickel-zinc alloy, and tin-zinc alloy.

Abstract: A gearbox adapted for use with a gas turbine engine and a method for making the same are disclosed herein. The gearbox comprising a housing made from a magnesium alloy, and an aluminum oxide coating on the magnesium alloy housing. The aluminum oxide coating may inhibit corrosion of the housing, and may have a nano-microcrystalline structure that defines an inner region bonded directly to the housing and an outer region spaced apart from the housing.

Abstract: A gearbox adapted for use with a gas turbine engine and a method for making the same are disclosed herein. The gearbox comprising a housing made from a magnesium alloy, and an aluminum oxide coating on the magnesium alloy housing. The aluminum oxide coating may inhibit corrosion of the housing, and may have a nano-microcrystalline structure that defines an inner region bonded directly to the housing and an outer region spaced apart from the housing.