Microstructure and mechanical properties of Nb-Si based alloys with addition of N

Abstract

In this paper, the effect of N addition on microstructure and mechanical properties of Nb-16Si-20Ti alloy was investigated. The nominal compositions of alloys are Nb-16Si-20Ti-xN (x = 0, 1, 2, 4, 8 at%). The research results show that the addition of N element will make the solidification path transfers from hypoeutectic to hypereutectic. TiN compound appears in all the N-contained alloys and grows up with the increase of concentration of N element. The transformation of silicide is verified by the Mediema and Toop thermodynamic model. The room-temperature fracture toughness of the alloys is ameliorated by addition of N element. Performance of 4 N alloy is the best, which is 50% higher than that of Nb-16Si-20Ti original alloy. Compressive strength increases 18.8% due to the grain refinement strengthening and solid solution strengthening caused by N element.