The Formation of Composite Nitride from Niobium-Titanium and Vanadium-Niobium Alloys

Abstract

Nitridings of 60 Nb-40 Ti (wt%) alloy powder (grain size is nearly 80 μ, Nb-Ti alloy plate (Nb : 20, 40, 60, 80wt%) and 50 V-50 Nb (wt%) alloy plate specimens with N2 (1 atm) atmosphere were carried out at 700∼1350°C. The nitriding processes were investigated by microscopic observation, X-ray diffractometry and X-ray microprobe analysis and the possibility of composite nitride formation was discussed. In the nitridings of Nb-Ti alloys, Ti-rich nitride precipitated as needle-like crystal remaining nitrogen poor Nb-rich nitride or alloy. But Ti-rich nitride and Nb-rich nitride (or alloy) phases reacted to form (Nb, Ti)N as nitriding proceeded further. In the nitridings of 60 Nb-40 Ti powder and Nb-Ti plate (Nb : 20, 40, 60, 80 wt%, thickness is nearly 0.3 mm) specimens, (Nb, Ti)N single phases were obtained at 1300°C, 4h and 1350°C within 48 h, respectively. In the nitriding of 50 V-50 Nb plate specimens (thickness is nearly 0.8 mm), needle-like nitride was not observed but a nitride layer with alloy composition developed from the surface into the inner part of specimen. (V, Nb)N single phases were obtained at 1350°C within 48 h. © 1981, The Chemical Society of Japan. All rights reserved.