Surface modification of AISI-4620 steel with intense pulsed ion beams

A 300 keV, 30 kA, 1 mu s intense beam of carbon, oxygen, and hydrogen ions is used for the surface treatment of AISI-4620 steel coupons, a common material used in automotive gear applications. The beam is extracted from a magnetically-insulated vacuum diode and deposited into the top 1 mu m of the target surface. The beam-solid interaction causes a rapid melt and resolidification with heating and cooling rates of up to 10(10) K/s. Treated surfaces are smoothed over 1 mu m-scale lengths, but are accompanied by 1 mu m-diameter craters and larger-scale roughening over greater than or equal to 10 mu m, depending on beam fluence and number of pulses. Treated surfaces are up to 1.8 x harder with no discernible change in modulus over depths of 1 mu m or more. Qualitative improvements in the wear morphology of treated surfaces are reported.