原位力学分析Al-Cu-Li合金晶界析出对滑移转移的影响

In Situ Mechanical Analysis of the Effect of Grain Boundary Precipitation on Slip Transfer in Al-Cu-Li Alloy

摘要: 本文以2060 Al-Cu-Li合金为研究对象，采用原位拉伸SEM/EBSD研究了该合金分别处于T4、T6热处理状态下在变形过程中的晶粒组织变化；对晶界处的滑移转移现象进行了具体地分析，并利用TEM表征晶界相和晶界附近位错组态。通过对比分析不同热处理状态下的滑移转移现象和晶界析出行为，研究晶界析出对滑移转移的影响。结果表明，同一试样不同晶界处的位错累积存在差异，主要原因是晶界处位错可透过性不同导致的；晶界变形协调因子Luster-Morris参数(m')可以较好地解释几何不存在析出相的晶界处的滑移转移现象；晶界析出对晶界与位错的交互作用存在影响，影响的强弱受晶界类型的制约。对于时效态Al-Cu-Li合金的大角度晶界，由于CSL晶界具有较低的能量，往往在时效过程中更易析出连续的T₁相，导致与一般的晶界相比，几何判定准则难以准确反映CSL晶界处的滑移转移现象。

Abstract: In this paper, the 2060 Al-Cu-Li alloy was taken as the research object, and the grain structure changes of the alloy during deformation were studied using in-situ tensile SEM/EBSD under T4 and T6 heat treatment conditions, respectively; a specific analysis was conducted on the slip transfer phenomenon at grain boundaries, and TEM was used to characterize the grain boundary phases and dislocation configurations near grain boundaries. By comparing and analyzing the slip transfer phenomenon and grain boundary precipitation behavior under different heat treatment states, the influence of grain boundary precipitation on slip transfer is studied. The results indicate that there are differences in the accumulation of dislocations at different grain boundaries in the same sample, mainly due to the different permeability of dislocations at grain boundaries; The Luster Morris parameter (m') can effectively explain the slip transfer phenomenon at grain boundaries where there are no precipitated phases in geometry; The precipitation of grain boundaries has an impact on the interaction between grain boundaries and dislocations, and the strength of the impact is constrained by the type of grain boundary. For the large angle grain boundaries of aged Al-Cu-Li alloys, due to the lower energy of CSL grain boundaries, continuous T₁ phases are more likely to precipitate during the aging process, making it difficult for geometric judgment criteria to accurately reflect the slip transfer phenomenon at CSL grain boundaries compared to general grain boundaries.