Low-Temperature Steel Boronization Through Dynamic Ion Mixing

Mild steel substrates were treated with B-ion implantation or dynamic ion mixing in which B-ion implantation and Ti-deposition were conducted simultaneously. Prior to treatment, some substrates were implanted with C-ions to confirm the location of the original substrate surface. Compositional depth profiles of surface regions were obtained by using Auger electron spectroscopy (AES). For B-ion implantation, implanted B species accumulate with the outward transport of Fe atoms followed by growth of a monolithic B layer. For dynamic ion mixing, this outward Fe-atom transport is enhanced further, apparently due to the trapping of sputtered Fe atoms by condensing Ti atoms on the surface. This Fe-Ti reaction causes Fe atoms to be incorporated into the growing B layer, resulting in the formation of a 3μm-thick boronized layer at less than 200°C.