Al-Li-Cu-Zr合金中T_1相结构、形核和长大机制研究

Study on T_1 Phase Structure, Nucleation and Growth Mechanism in Al-Li-Cu-Zr Alloy

T_1(Al_2CuLi)相是Al-Li-Cu-Zr合金中的重要强化相。通过TEM在对T1相结构和形貌分析的基础上,构造了T1相的结构。T1相晶核以ABCBA的堆垛顺序,共由36个原子组成,其晶格常数a=0.495nm,c=0.933nm。与基体的位相关系为:狖0001狚T1∥狖111狚α,<1010>T1∥<110>α。合金中铜原子的偏聚降低了基体的层错能,从而为T1相依赖扩散层错形核提供了有利条件。T1相长大依赖于原子扩散和台阶滑移,是一种长程扩散控制的台阶机制。

T-1 phase is an important strengthening phase for Al-Li-Cu-Zr alloy. The phase structure of T-1 was constructed on basis of the investigation and morphology observation by means of transmission electron microscope. It is concluded that the crystal lattice of T-1 phase is composed of 36 atoms with ABCBA stacking sequence. The crystal parameters are a = 0.495nm and c = 0.933nm with the orientation relationship of (0001)(tau1)//{111}(alpha) and <10 (1) over bar0>(tau1)//<110>(alpha) to the matrix. For the studied alloy, the aggregated copper atoms reduced stacking faulting energy of the Al matrix favourable to the nucleation and growth of T-1 phase. The growth of T-1 phase is of long-term controlled diffusion mechanism depending on the atoms diffusion and ledge slipping.