An experimental and numerical study of novel nano-grained (γ+ α2)-TiAl/Al2O3 cermets.

In this paper, a microstructure-based finite element model for nano-grained (!+↵2)-TiAl/Al2O3 cermets is proposed based on a modified variational formulation of the Gurson model for an elastic-plastic porous material. In the modeling approach, the high volume fraction of alumina, variability in material characteristics, and microstructural features (e.g., inclusion size) are considered. Mechanical properties and microstructure inputs are derived from nanoindentation and microscopy analysis performed for this study, as well as using available information in the literature. Once developed, modeling results are validated against experimental quasi-static compressive stress-strain measurements using digital image correlation techniques. The validation is extended by comparing experimental observations and computational outputs of the ratio of the lateral to axial strain (as a measure of deformation), and reasonable agreement is found. Once the model is validated for an experimentally known condition, the effect of varying the mechanical properties (e.g., strain hardening parameters and elastic modulus) and microstructure variables (e.g., alumina volume fraction and porosity) on material responses are then explored. These results serve as a foundation for future microstructure optimization.