Induction melting in cold crucible furnace for the production of components in turbine applications

In the last two decades, the interest towards Nb-MASC, (i.e. niobium-Metal and Silicide Composite) alloys has grown significantly because of their promising mechanical properties. Their tolerance to high temperatures drove much research aimed at the production of components operating in severe environments, in particular, blades of turbines for land and aircraft applications. However, the manufacture of Nb-MASC alloys still encounters multiple challenges, primarily stemming from the chemical reactivity of liquid niobium and the frequent non-homogeneity of the solid cast. To overcome such complications, this work proposed the employment of induction melting in the cold crucible furnace. It was demonstrated that a binary Nb-18Si compound could be alloyed with excellent homogeneity using a single melt under vacuum atmosphere. On the other hand, a six-component Nb-16Si-22Ti-4Cr-3Al-2Hf compound required multiple melting steps of the same sample and argon atmosphere to obtain satisfactory homogeneity of the cast. In general terms, this work demonstrates the induction cold crucible furnace to be an energy-efficient solution for the manufacture of highly homogeneous samples on a laboratory scale and a valuable alternative to the alloying strategies employed until now. Tables 3, Figs 4, Refs 21.