Nb-Si-B계에서 Nb+T2 공존 영역의 미세조직 특성

Abstract

Intermetallic-based materials are interesting for high temperature structural applications because of their good mechanical properties and enhanced oxidation resistance. In this study microstructural examination of the Nb-Si-B alloys at Nb-rich compositions was performed. The Nb-rich corner of the Nb-Si-B system is very attractive because the constituent phases are Nb (a ductile and tough phase with a high melting temperature) and T-2 (a very hard intermetallic compound with favorable oxidation resistance), which make a good combination for high temperature structural materials. At compositions lower than 82 at%Nb the microstructure shows the T-2 primary phase and eutectic (T-2+Nb), while the Nb primary phase and eutectic were formed at higher compositions. Hardness tests (Rockwell A-scale and micro Vickers) were carried out to estimate the optimal composition for good mechanical properties.