Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

Abstract

In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1GPa when the treated temperature is 823K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.