Cobalt-Niobium-Vanadium

Joel Fels, Afina Lupulescu, Marlena Ostrowska, Giacomo Roncallo, Zhao Wenjiao and Andy Watson

Introduction

The main strengthening mechanism for Ni-based superalloys is through the precipitation of the ordered L1₂ γʹ phase, which is different from that traditionally employed in Co-based alloys, which depends on precipitation of carbides. However, ternary phases with the L1₂ structure have been seen in the Al-Co-W system making the prospect of developing high-strength Co-base alloys as possible replacements for Ni-based superalloys in high-temperature aerospace applications very attractive [2006Sat]. The properties of Co-base alloys can be improved through the addition of alloying elements such as Nb and V. Vanadium additions enhance the ductility, strength and corrosion resistance of Co-based materials. Nb forms the solid-solutions with Co, which improve the high-temperature stren...