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运用大规模的分子动力学模拟研究了厚度和晶粒取向对纳米晶Al薄膜Bauschinger效应的影响.模拟结果表明:晶粒取向的不均匀性对早期Bauschinger效应及相关塑性变形机制有显著的影响.相对于没有织构的薄膜试样而言,尽管晶粒尺寸、形状和厚度相同,具有(110)织构的薄膜表现出较轻微的Bauschinger效应.同时,分子动力学模拟也揭示早期Bauschinger效应起源于卸载过程中位错的反向运动和由于位错反应造成位错密度的降低.这些位错机制是由加载过程中产生的不均匀变形引起的内在残余应力所驱动的.
The effects of thickness and grain orientation on the Bauschinger effect of nanocrystalline Al thin films were investigated by large-scale molecular dynamics simulations. The simulation results show that the non-uniform grain orientation has a significant effect on the Bauschinger effect and the related plastic deformation mechanism. The thin film with (110) texture shows a slight Bauschinger effect compared to the textured sample without the same Bauschinger effect, though the grain size, shape and thickness are the same.Meanwhile, molecular dynamics simulation also reveals the origin of early Bauschinger effect The reverse movement of dislocations during unloading and the decrease of dislocation density due to dislocation reactions are driven by the inherent residual stresses caused by the inhomogeneous deformations during loading.