방전 플라즈마 소결(Spark Plasma Sintering) 방법에 의해 제조된 Nb-Si-B계 합금의 미세조직 특성

Abstract

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 favorable in that the constituent phases are Nb (ductile and tough phase with high melting temperature) and T2 phase (very hard intermetallic compound with favorable oxidation resistance) which are good combination for high temperature structural materials. The samples containing compositions near Nb-rich corner of the Nb-Si-B ternary system were prepared by spark plasma sintering (SPS) process using T2 and Nb powders. T2 bulk phase was made in arc furnace by melting the Nb slug and the Si-B powder compact. The T2 bulk phase was subsequently ball-milled to powders. SPS was performed at 1300oC and 1400oC, depending on the composition, under 30 MPa for 600s, to produce disc-shaped specimen with 15 mm in diameter and 3 mm high. Hardness tests (Rockwell A-scale and micro Vickers) were carried out to estimate the mechanical property.