Consequences of partial {Hf by Ta}-Substitution on the High Temperature Properties of a HfC-Reinforced Ni-based Superalloy

Overview & Synopsis

Hafnium carbides have recently demonstrated high interest to strengthen equi-axed polycrystalline superalloys. Notably chromia-forming Nibased alloys reinforced by HfC appeared as being both oxidation-resistant and creep-resistant at temperatures higher than 1000°C. Since high contents in Hf are required for achieving such high performances it can be interesting to investigate possibilities of partial replacement of this expensive and rather rare element by tantalum. In this work two levels of partial substitution were tested. Two alloys were elaborated by foundry and subjected to creep and oxidation tests at 1100°C. The obtained results show that the two alloys are capable of good creep-resistance and very good oxidation behavior at this particularly high temperature for superalloys not protected by thermal barrier coating.