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本文用高压电镜研究了Zr在高静液压下,挤压变形后形成的位错亚结构。在10％变形率下,位错以复杂二维纠结形态密集于(1010)活动滑移面上;到30％变形率时,发展为以这些活动滑移面为界面,间距0.5μm左右的平行片层结构。在1200MPa下挤压70％后,普遍形成形态清晰、界面位向差达3—5°以上的片层状亚晶群。亚晶群从其晶体学特征上分成两类:一类是在早期变形时形成的平行(1010)面的亚晶的基础上,进一步发展起来的倾侧型亚晶;另一类亚晶界面平行于基面(0001),并呈扭转晶界特征。后者比前者数量更多,厚度更小(0.1—0.3μm),但在较小变形量下不出现。通过与常规拉拔Zr的比较,可以肯定上述现象是静液挤压条件下形成的特殊的位错亚结构,高静液压对位错热激活运动的影响可以解释这种特殊亚结构的形成。
In this paper, the dislocation sub-structure of Zr formed by extrusion under high hydrostatic pressure was studied by high-pressure electron microscope. At 10% deformation, the dislocations are densely packed with (1010) active slip planes in a complex two-dimensional tangled form. When the deformation rate is 30%, these active slip planes are developed as interfaces with a pitch of about 0.5 μm Lamellar structure. After pressing at 70% at 1200MPa, the lamellar sub-group with clear morphology and interfacial orientation difference of 3-5 ° or more was formed. Sub-crystallites are divided into two types based on their crystallographic features: one is the further development of the tilted subgrains based on the parallel (1010) plane subgrains formed during the early deformation; the other is subgrain parallel On the basal plane (0001), and is characterized by torsion grain boundaries. The latter is larger in number and smaller in thickness (0.1-0.3 μm), but does not appear with smaller deformations. By comparison with the conventional drawing Zr, it can be concluded that the above phenomenon is a special dislocation sub-structure formed under hydrostatic extrusion. The effect of high hydrostatic pressure on the dislocation heat-activatable movement can explain the formation of this special sub-structure.