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采用表面机械研磨的方法,在Al-Zn-Mg合金表面获得了厚20μm、晶粒尺寸为20~25 nm的纳米晶化层,使其表层硬度提高了约4倍。经透射电镜(TEM)观察发现,铝合金在表面机械研磨的过程中,原始粗晶粒内部出现位错墙和位错缠绕结构。随着变形量的增大,位错墙和位错缠绕结构逐步演变成小角度取向差的亚晶界,直至变成大角晶界,形成了纳米晶化层。
Surface mechanical grinding method was used to obtain the nanocrystalline layer with a thickness of 20μm and a grain size of 20-25nm on the surface of Al-Zn-Mg alloy, and the surface hardness was increased about 4 times. Transmission electron microscopy (TEM) observation showed that the surface of the aluminum alloy in the process of grinding, dislocation walls and dislocation winding structure within the original coarse grain. With the increase of the deformation, the dislocation wall and the dislocation winding structure gradually evolve into a sub-grain boundary with small angle misorientation until it becomes a large-angle grain boundary, forming a nanocrystalline layer.