Abstract: A co-deposit of aluminum, zinc and tin can be deposited onto metallic substrates including small metal parts, and the co-deposit is strongly adherent to the substrate and exhibits improved corrosion resistant properties. The co-deposits are plated onto metallic substrates by a process which comprises the steps of a. preparing the substrate to receive the co-deposit, b. forming a slurry comprising a soluble source of stannous ions, impact media, and aluminum and zinc in particulate form in a liquid medium maintained at a pH below about 4, c. mechanically impacting the slurry against the surface of the metallic substrate in a plating container to plate a co-deposit of tin, aluminum and zinc on a metal surface, d. renewing the stannous ions, aluminum and zinc in the slurry while maintaining the pH of the slurry below about 4 throughout the plating process until a co-deposit of the desired thickness is obtained.