(1. 西北有色金属研究院，西安 710016；
2. 西安交通大学 材料科学与工程学院，西安 710049)
摘 要: 通过表面机械碾磨处理(SMGT)对TA2纯钛进行加工并实现表面纳米化，采用光学显微镜、扫描电镜 (SEM)和透射电镜(TEM)等技术手段观察和分析其表层剧烈变形后的组织以及心部未变形组织，并研究梯度结构表层对纯钛断裂机制和变形方式的影响。结果表明：经过SMGT处理后，TA2纯钛拉伸断口表层韧窝尺寸呈随距表层深度减小而逐渐减小的梯度结构分布；表层纵向剖面表现出与粗晶心部不同的平整剪切状形态；同时断口侧表面并没有明显的变形痕迹，颈缩变形后依然比较光滑平整。
关键字: 纯钛；表面机械碾磨处理；梯度结构表层；拉伸性能；韧窝；断裂机制
（1. Northwest Institute for Nonferrous Metal Research, Xi’an 710016, China;
2. School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China）
Abstract:Surface mechanical grinding treatment (SMGT) was used to fabricate a gradient nano-micron-structured surface layer on commercially pure titanium TA2. The microstructures of deformed surface layer and undeformed matrix were researched by OM, SEM and TEM, and the effects of gradient nano-micron-structured surface layer on overall fracture and deformation mechanisms were discussed. The results reveal that dimple size presents a gradient tendency from 1 μm in the treated surface layer to 23 μm in the matrix. For SMGT Ti, the longitudinal section of surface layers shows smooth shear fracture surface. Different from coarse-grained samples, no obvious trace of deformation is observed on the lateral surfaces of SMGT Ti.
Key words: pure titanium; surface mechanical grinding treatment; gradient nano-micron-structured layer; tensile property; dimple; fracture mechanism
