Nb-Si-B계에서 Nb+T2 공존 영역의 미세조직 특성

Abstract

Intermetallic-based materials are interesting for high temperature structural applications becauseof their good mechanical properties and enhanced oxidation resistance. In this study microstructuralexamination of the Nb-Si-B alloys at Nb-rich compositions was performed. The Nb-rich corner of the Nb-Si-Bsystem is very attractive because the constituent phases are Nb (a ductile and tough phase with a high meltingtemperature) and T2 (a very hard intermetallic compound with favorable oxidation resistance), which makea good combination for high temperature structural materials. At compositions lower than 82 at%Nb themicrostructure shows the T2 primary phase and eutectic (T2+Nb), while the Nb primary phase and eutecticwere formed at higher compositions. Hardness tests (Rockwell A-scale and micro Vickers) were carried outto estimate the optimal composition for good mechanical properties.