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在室温下以等径弯曲通道变形(ECAP)技术制备超细晶工业纯钛,利用光学显微镜(OM)和透射电子显微镜(TEM)研究室温ECAP变形纯钛微观组织演变过程,并讨论纯钛室温ECAP变形的显微组织演化机制。结果表明:显微组织演化分为3个不同阶段,分别对应3种不同机制:第一阶段在真应变ε≤1.27时,为位错滑移和孪生交互作用细化机制,形成含有高密度位错和孪晶的板条状组织;第二阶段在真应变量1.27<ε<2.54时,为动态回复细化机制,晶粒进一步细化至~0.25μm,形成典型的变形亚晶组织;第三阶段在真应变量ε≥2.54时,为不平衡晶界的转动细化机制,形成平均晶粒尺寸约为0.2μm的等轴状大角度晶界超细晶组织。
Ultrafine-grained industrial pure titanium was prepared by ECAP at room temperature. The microstructure evolution of pure titanium at room temperature ECAP was studied by optical microscope (OM) and transmission electron microscope (TEM) ECAP deformation of the microstructure evolution mechanism. The results show that the microstructural evolution is divided into three different stages, which correspond to three different mechanisms respectively: In the first stage, when the true strain ε ≤ 1.27, the mechanism of dislocation slip and twin interaction refinement, the formation of high density In the second stage, when the true strain is 1.27 <ε <2.54, the grain is further refined to ~0.25 μm to form a typical deformed subgrain structure. In the third stage, when the true strain ε≥2.54, the mechanism of grain refinement for the unbalanced grain boundaries is formed, and an equiaxed, large-angle grain boundary ultrafine grain structure with an average grain size of about 0.2 μm is formed.