Investigation of microstructural influences on the micro-macro deformation of a two-phase g-TiAl alloy using a multiscale approach combined with crystal plasticity

Abstract

-TiAl alloys are very promising for high temperature structural applications due to their excellent thermo-mechanical properties. The main drawbacks of these alloys are low ductility and high brittleness, which lead to catastrophic failure during operation. These shortcomings can be improved by optimizing alloy design, production route and microstructure. Therefore, a clear understanding of the microstructural influences on the deformation behavior is highly required. Following this aim a duplex TiAl alloy has been investigated experimentally and numerically. This microstructure consists of lamellar colonies with ()TiAl-phases and globular grains with TiAl-phase. The microstructure has been characterized by SEM and TEM analysis and the most important structural features (e.g., vol. % of grains and colonies, their orientation, size, and presence of phases) are idealized for the micro-meso FE modeling. The micro-meso descriptions are linked with the two-scale FE2 approach. The constitutive behavior of the individual phases was described in a crystal plasticity model. Simulations have been performed to understand the deformation mechanisms of the TiAl alloy at local and global scale and the important crystallographic deformation modes that are important for the global alloy responses have been predicted. This understanding of the microstructure-property correlation delivers important information for further alloy optimization.