Structure and Composition of Scales Formed on AISI 316 L Steel Alloyed with Ce/La Using High Intensity Plasma Pulses after Oxidation in 1000°C

It is well documented that the high oxygen affinity elements such as Y, Ce, La, Er and other rare earth elements added to steel in small amounts can improve their high temperature oxidation resistance. Rare earth elements can be either alloyed during the steel making process or introduced through surface treatment techniques. Improvement of high temperature oxidation resistance of AISI 316 L steel by incorporation Ce and La elements into its near surface region using high intensity pulsed plasma beams in so-called deposition by the pulse erosion mode was investigated in the present work. The samples were irradiated with 3 short (μs scale) intense (energy density $3 J//cm^2$) plasma pulses. Heating and cooling processes occur under non-equilibrium conditions. In all samples the near surface layer of the thickness in μm range was melted and simultaneously doped with cerium and lanthanum. The modified samples were oxidized at 1000°C for 100 h in air. The obtained effects were: oxide scales formed on the treated samples were more fine-grained, compact and adhering better that those formed on the un-treated samples.