表面纳米化对工业纯钛拉伸性能的影响
Effects of Surface Nano-crystallization on Tensile Properties of Commercial Pure Titanium
张聪惠, 何晓梅, 刘晓燕, 赵西成
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作者单位：(西安建筑科技大学 冶金工程学院, 陕西 西安 710055)
中文关键字：工业纯钛； 表面纳米化； 拉伸性能
英文关键字：commercial pure titanium (CP-Ti); surface nano-crystallization; tensile properties
中文摘要：通过SMAT技术实现了工业纯钛表面纳米化，并利用X射线衍射(XRD)、扫描电镜和高分辨率透射电子显微镜(HRTEM)分析技术对表面纳米结构层进行了表征，对比研究了工业纯钛和经SMAT处理表面纳米化工业纯钛的拉伸性能，讨论了表面纳米化对工业纯钛拉伸性能的影响。结果表明：经SMAT处理后，由于表面纳米晶的形成和变形层中高密度的孪晶与位错共同的作用，工业纯钛的屈服强度、抗拉强度提高而伸长率降低。 试样经SMAT处理后，沿处理面到中心晶粒尺寸不同，使得SMAT试样拉伸断裂后处理面与中心的断裂类型不同，表面纳米晶层和亚晶层的断裂主要是滑移分离断裂，而基体粗晶部分断裂为微孔聚集型断裂。
英文摘要：A nano-structured surface layer was obtained on the surface of CP-Ti by surface mechanical attrition treatment(SMAT), and the nano-structured surface of the SMAT sample was analyzed by means of X-ray diffraction(XRD), scanning electron microscope(SEM) and high-resolution electron microscope(HRTEM). The tensile properties of bulk Ti and nano-crystalline Ti processed by SMAT were studied. The results of tensile tests indicate that the surface nano-crystallization leads to an increase in yield strength and ultimate tensile strength and a decrease in uniform elongation compared with as-received ones. After SMAT, the grain size trends to increase from the surface to the initial part, and the fracture mechanism is also different among the nano-structured surface layer, submicro-fine grained layer and the coarse grain layer. The fracture in the nano-structured surface layer and submicro-fine grained layer is mainly gliding fracture, but that in the coarse grain layer is mainly dimple fracture.