对Al-12.7Si合金进行表面机械研磨处理, 在表层制备纳米-微米梯度结构,利用XRD和TEM研究结构演变过程. Al-12.7Si合金形变诱发的纳米化机理归纳如下:在外加载荷的反复作用下, Al基体高密度位错通过滑移、湮灭和重组形成位错胞/亚微晶;通过不断吸收位错, 位错胞/亚微晶之间的取向差逐渐增大; 亚微晶内高密度位错重复上述过程, 使晶粒尺寸减小、取向差增大, 最终形成等轴状、取向呈随机分布的纳米晶.Si颗粒通过内部位错单滑移或多滑移所产生的切割及部分溶解而细化, 并随着Al基体的塑性流动而呈弥散分布.
Gradient nano–micro–structured surface layer was synthesized on Al–12.7Si alloy by means of surface mechanical attrition treatment. The microstructural evolution was examined by XRD and TEM. The surface intense deformation induced nanocrystallization mechanism was summarized as follows: upon the application of repeated loads, dislocation cells/sub–micro–grains form through slips, annihilations and recombinations of high density of dislocations in Al coarse grains. The misorientations between the dislocation cells/sub–micro–grains increased by cotinuously absorbing more dislocatons. High density of dislocations in sub–micro–grains developing in above route led to the redction of grain size and the increment of misorientatins between the refined grains, and finally equiaxed nc grains with random orientations formed. The refinement of Si particles was found to be carried out through single–or multi–slips of internal dislocations and partial dissolution, then the refined Si particles distributed niformly due to the plastic flows in Al matrix.
[1] Lu K, Lu J. Mater Sci Eng, 2004; A375–377: 38
[2] Wu X, Tao N, Hong Y, Xu B, Lu J, Lu K. Acta Mater, 2002; 50: 2075
[3] Wang K, Tao N R, Liu G, Lu J, Lu K. Acta Mater, 2006; 54: 5281
[4] Zhu K Y, Vassel A, Brisset F, Lu K, Lu J. Acta Mater, 2004; 52: 4101
[5] Sun Q, Shi Y N, Zhng X, Lu K. Acta Mater, 2007; 55: 975
[6] Wu X, Tao N, Hong Y, Liu G, Xu B, Lu J, Lu K. Acta Mater, 2005; 53: 681
[7] Tao N R, Wang Z B, Tong W P, Sui M L, Lu J, Lu K. Acta Mater, 2002; 50: 4603
[8] Zhang H W, Hei Z K, Liu G, Lu J, Lu K. Acta Mater, 2003; 51: 1871
[9] L¨u A Q, Liu G, Liu C M. Acta Metall Sin, 2004; 40: 943
(吕爱强, 刘 刚, 刘春明. 金属学报, 2004; 40: 943)
[10] Wang Z B, Tao N R, Li S, Wang W, Liu G, Lu J, Lu K. Mater Sci Eng, 2003; A352: 144
[11] Ba D M, Ma S N, Meng F J, Li C Q. Surf Coat Technol, 2007; 202: 254
[12] Zhang Y S, Wang K, Han Z, Liu G. Wear, 2007; 262: 1463
[13] Wang T, Wang D P, Liu G, Gong B M, Song N S. Appl Surf Sci, 2008; 255: 1824
[14] Wei Y H, Liu B S, Hou L F, Xu B S, Liu G. J Alloy Compd, 2008; 452: 336
[15] Zhou L, Liu G, Ma X L, Lu K. Acta Mater, 2008; 56: 78
