钒的晶界体积收缩
Volume Contraction at a Grain Boundary in Vanadium
摘要：
传统观点认为，晶体中晶界处的对称性破坏会引起体积膨胀，并且在任何种类的晶体中，都没有证实晶界处体积收缩的证据。我们报告了令人惊讶的体积收缩在Sigma3（111）钒晶界。发现该晶界附近的晶格畸变将局部结构推向假设的ω相，其仅比bcc相稍微不稳定。将ω相的晶格常数a压缩到bcc的值，如在Sigma3（111）晶界处的情况，导致比bcc结构更小的c，因此体积收缩。我们还发现，这种体积收缩阻碍了Ti和H的偏析，同时增强了Cr的偏析，因此对材料性能产生了显着影响。这一发现增加了凝聚态物质的基本新知识，也可能指向通过体积控制新材料晶界工程的新技术。
英文摘要：
It is a conventional wisdom that symmetry breakdown at grain boundaries in crystals introduces volume expansion and there has been no confirmed evidence of volume contraction at a grain boundary in any kind of crystals. We report surprising volume contraction at the Sigma3(111) grain boundary in vanadium. The lattice distortion near this grain boundary is found to drive the local structure toward a hypothetical ω phase, which is only slightly less stable than the bcc phase. Compressing lattice constant a of the ω-phase down to the value of bcc, as is the case at the Sigma3(111) grain boundary, results in smaller c than in bcc structure, and hence the volume contraction. We also find such a volume contraction impedes the segregation of Ti and H, while enhances that of Cr, and hence a significant influence on material properties. The discovery adds fundamental new knowledge of condensed matter, and may also point to new techniques in grain boundary engineering of novel materials through volume control.
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