This image depicts the carburization process used to harden the surface of steel components. The steel is exposed to a gaseous carbon-containing atmosphere, and the carbon atoms diffuse into the steel, hardening it. If the diffusivity of carbon into steel at the carburization temperature of 1000C is 10 (microns) 2/s and carburization is undertaken for 160s, what is a good estimate for the average distance the carbon has diffused into the steel? 1.6 microns 40 microns 400 microns 1600 microns 160 microns