High Temperature Deformation Mechanism Maps for γ-TiAl Based-alloys with DP/NG Structures: Construction and Application

Once the metallic materials are subject to stress, a number of independent or alternative mechanisms may initiate and contribute to deformation. As for the γ-TiAl-based alloys whose deformation kinetics is fairly complex, it is of particular significance to quantify the general constitutive relationship produced by each possible mechanism and to identify the predominant mechanism at any specific loading conditions. For this purpose, in the present study Ashby-type deformation mechanism maps concerning six major deformation mechanisms were constructed for various TiAl alloys with duplex (DP) and near-gamma (NG) microstructures. The general features as well as the effect of grain size on the appearance of the maps were analyzed. After a detailed discussion, it is believed that the proposed deformation mechanism maps are powerful tools in understanding the deformation mechanisms and predicting the deformation kinetics of DP/NG-TiAl alloys. In particular, they are demonstrated to be useful reference in alloy design and determination of proper processing parameters.