双态/近γ组织TiAl合金的变形机制图谱：构建及应用

High temperature deformation mechanism maps for γ-TiAl based-alloys with DP/NG structures: Construction and application

摘要:

当金属材料承受应力时，某些独立或非独立的变形机制可同时被激活。对于变形动力学极其复杂的γ-TiAl基合金，定量描述每个变形机制的一般性本构行为、预测指定加载条件下的主要变形机制具有非常重要的科学和实际意义。为此，本研究针对具有双态/近γ组织的TiAl合金，构建了同时考虑六种机制的变形机制图谱，并详细分析了其形貌特征，探讨了晶粒度的影响。研究表明，本研究所提出的变形机制图谱是理解TiAl合金变形机制、预测变形动力学的有力工具。特别是该变形机制图谱可为TiAl合金设计及变形工艺制定提供重要借鉴。

Abstract:

Once the metallic materials were subject to stress, a number of independent or alternative mechanisms may initiate and contribute to the 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 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 have been 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 have been analyzed in detail. After a detailed discussion, it was believed that the proposed deformation mechanism maps were powerful tools in understanding the deformation mechanisms and predicting the deformation kinetics of DP/NG-TiAl alloys. Especially, they were demonstrated to be useful reference in alloy design and determination of proper processing parameters.