【摘要】 采用超音速微粒轰击(SFPB)技术对铝合金2A14进行表面纳米化处理,利用X-射线衍射仪和透射电镜等研究材料表层的组织变化机理。结果表明:材料表面经强烈塑性变形形成30μm厚的纳米层,平均晶粒大小约为30 nm,平均微观应变为0.1294%。观察发现距表面200μm处的应变层存在纳米级位错胞,通过理论分析提出铝合金表面纳米晶层新的形成机理,原始粗晶被快速地一次分割成纳米级位错胞或层状胞块组织,随着胞壁柏氏矢量不断积累,晶粒的取向差不断增大形成纳米级亚晶,通过晶界滑移或晶体转动形成均匀、等轴、随机的纳米晶粒。更多还原

【Abstract】 By means of supersonic fine particles bombarding( SFPB),a nanostructured surface layer was formed on 2A14 aluminum alloy plate. Mechanism of material surface structure change was systematically characterized by using X-ray diffraction( XRD) analysis and transmission electron microscopy( TEM) observations. The results show that 30 μm thick nanostructured layer is formed when induced by severe plastic deformation,and the average grain size is 30 nm,the average micro strain is 0. 1294%. Based on the experimental observations,nanoscale dislocation cells exist in strain layer about 200 μm from the surface. A new formation mechanism of nanocrystalline layer on aluminum alloy surface is presented by theoretical analysis. The original grains are segmented quickly into nanoscale dislocation cell or lamellar cell,transformation of cell walls into subboundaries with large misorientations by accumulating more dislocations. Eventually,equiaxed nanocrystallites with random crystallographic orientations are formed by grain boundary sliding or grain rotating.更多还原