Creep Behavior at Elevated Temperatures of Several Polycrystalline Ni-based Superalloys Strengthened by MC-Carbides

Overview & Synopsis

Conventional casting allows producing componentswith complex geome- tries and coarse grains favorable for good creep-resistance at high temperatures. Their weak points are generally their intergrains and interdendritics boundaries. Introducing carbon and MC-former metals can achieve the development of an intergranular and interdendritic network of eutectic carbides bringing the double benefit of a script-like geometry for the interdendritics cohesion, and of a good morphological and volume fraction stability on long times at high temperature. In this work two kinds of superalloys were obtained by high frequency induction foundry under inert atmosphere. The first ones are nickel-based superalloys reinforced by ZrC carbides. The second ones are also nickel-based alloys but strengthened by (Ta, Hf)C carbides. All were subjected to 3-points bending creep tests at 1100 °C for a maximal induced tensile stress equal to 20 MPa. They demonstrated high resistance despite the test temperature particularly high for superalloys produced by classical foundry.