非当量成分Ni_3Al基合金的有序─无序转变

Order-disorder Transition Behaviors of Non-stoichiometrical Ni_3Al

利用建立在EAM（EmbeddedAtomMethod）势基础上的等效原子模型，计算了模拟非当量成分的Ni3Al基合金结构稳定性与长程有序（LRO）度的关系，结果说明：非当量成分下，Ni3Al基合金有序无序转变温度随Al含量的增加而上升；其有序无序转变为形核长大的非均匀转变过程，理论上不存在稳定的均匀部分有序结构；其介稳的部分状态组织为完全有序区和完全无序区的混合组织．该结果能解释实验中所观察到的Ni3Al基合金有序无序转变。

The effective atom model based on EAM potential was applied to studythe relationship between the structural stability and the long range order parameter of non-stoichiometrical Ni3Al based alloys. The calculated results indicate that the order-disordertransition temperature (Tt) increases with Al composition increasing. The order-disorder tran-sition process is a nucleation-propagation process. The microstructure of partially orderstate is a mixed microstructure with full disorder and full order domains. The calculatedresults are consistent with the experimental results.