Size Effects in the Surface Properties of Electroplated Alloys between Iron Group Metals and Tungsten

Factors leading to size-dependent surface properties of electroplated coatings obtained by induced codeposition of iron group metals and tungsten are investigated. The size effect in microhardness described in earlier studies and the size effect in the corrosion resistance revealed in this work are shown to stem from a common origin, which is the formation of surface oxides. Removing surface oxides by abrasive processing leads to a higher corrosion rate and cancels the size effect in microhardness. Factors contributing to the formation of surface oxide layers during induced codeposition of considered alloys are studied.