Alloying the near surface layer of stainless steel with rare earth elements (REE) using high intensity pulsed plasma beams (HIPPB)

摘要

Addition of some active elements such as yttrium, cerium, lanthanum and other rare earths elements (REE) to austenitic stainless steels helps to improve their high temperature oxidation resistance and tribological properties. The high intensity plasma pulses were used to introduce Ce and La into AISI 316L (EU 1.4435) austenitic stainless steel. The plasma pulses contained both ions/atoms of Ce-La and those of the working gas. The pulse energy densities were sufficient to melt the near surface layer of the steel and introduce those elements into the surface layer. Scanning electron microscopy (SEM) as well as energy dispersion spectroscopy (EDS) was used for surface characterisation. Morphology of the surface layer changed but an austenitic phases (FCC) were identified in the modified layer. Modified material showed improvement of tribological properties as compared with initial one. Oxide scales formed on modified material are more finegrained and adhere better that those formed on the untreated ones.