Experimental and modelling methodologies for fatigue crack nucleation around non-metallic inclusions in polycrystalline Ni-base superalloy.

Powder metallurgy has become the preferred method for producing nickel-superalloy turbine disks. An unavoidable side-effect of powder metallurgy is the propensity to include non-metallic agglomerates in the nickel matrix. These inclusions may create a locally active stress field that may drive the nucleation of cracks. Recent studies have investigated different criteria for crack nucleation at room temperature. The real working conditions of a jet engine turbine are at high temperature and work remains to be done on crack nucleation in such an environment. This project aims to investigate the criteria for which cracks appear around an inclusion subject to high-temperature conditions by using experimental and modelling techniques.