表面机械研磨工业纯钛表面纳米化研究

表面机械研磨处理可以使工业纯钛形成纳米表面层, 通过扫描电镜、透射电镜和高分辨电镜观察SMAT处理后的工业纯钛表层组织, 并研究了工业纯钛表面纳米化机制. 工业纯钛表面纳米化机制为: 孪晶的形成和孪晶的交割使得原始晶粒尺寸减小, 同时使晶格取向发生改变, 有利于位错滑移; 孪晶通过自身交割, 以及位错密度增加及其相互作用, 形成了细小的孪晶与胞状组织; 胞状组织转变为多边形亚晶; 亚晶不断吸收位错形成大角度晶界, 亚晶以及取向不同的细小孪晶逐渐转变为随机取向的纳米晶.

Mechanism of Surface Nanocrystallization of Titanium during Surface Mechanical Attrition

A nanostructured surface layer was obtained by surface mechanical attrition treatment (SMAT). The microstructural evolution of the SMAT sample was analyzed by means of scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution electron microscope (HRTEM). A grain refinement mechanism was proposed as follows: the formation of twins and twin-twin intersection induced the decrease of the original grain size; the lattice orientation changed and was in favor of dislocation slip; with the delivery of twins, the interaction of twins with dislocation and the increase of dislocation density, the refined twins and cystiform microstructure were formed; the cystiform microstructure became polygonal ultracrystal; the ultracrystal became large-angle crystal boundary by continually absorbing dislocations, the refined twins with different orientation and the ultracrystal gradually transformed to nanocrystal of random orientation.