Modelling microstructure-property relationships of a multi-phase TiAl alloy using Crystal Plasticity

Abstract

The multi-phase TiAl intermetallics for the application in aero-engine turbine blades have complex microstructures. The mechanical behaviour of these alloys is influenced by two major grain structures, namely, single phase -grains (TiAl) and two-phase (2Ti3Al + TiAl) lamellar colonies. In the designing of components made of TiAl alloys the current approaches available in the integrated computational material engineering (ICME) lack advanced modelling strategies. For example, structural length scale for the complex material systems is often ignored or physics based constitutive behaviour of the alloy constituents is not considered. As an improvement we have developed a finite element based modelling approach that accounts for most important structural details covering a two-scale description of alloy microstructure (meso and micro) and incorporates a crystal plasticity constitutive model describing physics based deformation phenomena for prevailing phases. For the model input a series of experimental analyses using microscopy (TEM/REM) is required to generate representative microstructure data. Additional mechanical tests are needed for validating the model using global load-deformation responses. In the present work we will demonstrate the potentials of the modelling approach showing some predictive results for the deformation behaviour of a duplex TiAl alloy and discuss the sensitivity of microstructure on the overall alloy plasticity. It seems, the model is able to predict microstructure-property correlations of complex alloys up to reasonable accuracy. We expect to enhance the ICME based component design using this microstructure sensitive modelling approach.