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利用重复冲击变形技术对比研究了α钛合金Ti-2Al-2.5Zr和亚稳β钛合金Ti-10V-2Fe-3Al变形过程中的微观组织演化及纳米晶的形成机制。金相形貌、X射线衍射及透射电镜观察显示,对于Ti-2Al-2.5Zr合金,塑性变形先后经历了形变孪生、位错活动、剪切等3个过程。与之相反,对于Ti-10V-2Fe-3Al合金,马氏体相变主导着合金的变形。相变分割、剪切及逆向马氏体相变持续贡献于合金的晶粒细化。同时发现,尽管变形到应变量1.2时两类合金组织内均出现纳米晶,但是大量的透射形貌观察显示Ti-10V-2Fe-3Al合金中生成的纳米晶晶粒尺寸更小,纳米晶区域更大。这表明,变形过程中激活马氏体相变可加速材料的晶粒细化。
The microstructure evolution and nanocrystallization mechanism of Ti-2Al-2.5Zr α-Ti alloy and Ti-10V-2Fe-3Al metastable β-Ti alloy were studied by repeated impact deformation technique. Morphology, X-ray diffraction and transmission electron microscopy showed that the plastic deformation of the Ti-2Al-2.5Zr alloy underwent three processes of deformation twinning, dislocation activity and shearing. In contrast, martensitic transformation dominated the deformation of the Ti-10V-2Fe-3Al alloy. Phase change segmentation, shear and reverse martensitic transformation continue to contribute to the grain refinement of the alloy. It is also found that although the nanocrystal appears in both types of alloy structure when deformed to the strain of 1.2, the observation of a large number of transmission morphologies shows that the nanocrystalline grains generated in the Ti-10V-2Fe-3Al alloy are smaller in size and the nanocrystalline region Bigger This shows that the activation of martensitic transformation during deformation can accelerate the grain refinement of the material.