Chemical mixing and self-organization of Nb precipitates in Cu during severe plastic deformation
Chemical mixing and self-organization of Nb precipitates in Cu during severe plastic deformation
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DOI：
10.1016/j.actamat.2013.10.009
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发表时间：
2014
期刊：
影响因子：
9.4
通讯作者：
Miao Wang;R. Averback;P. Bellon;S. Dillon
中科院分区：
文献类型：
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作者：
Miao Wang;R. Averback;P. Bellon;S. Dillon
Cu、Ag和Nb三元合金（平均Nb含量为5，10和15at.%）的强塑性变形（SPD）Ag浓度为10原子%研究了高分辨率扫描电子显微镜，原子探针断层扫描和X射线衍射。将球磨的粉末压实，在600或950 °C下退火，随后在室温下通过高压扭转应变。在SPD过程中，Ag在Cu基体中重新均匀分布，但Nb的溶解度增加不到1%。此外，Nb沉淀物自组织成图案化的微观结构，由此它们的尺寸都落在以约20 nm为中心的窄分布内。对于给定的合金，该尺寸独立于初始微观结构，并且对Nb浓度不敏感。尺寸对剪切方法也不敏感。由于Nb扩散在室温下在Cu中可以忽略不计，因此这些结果确立了SPD单独可以在高度不混溶的合金中诱导成分图案化。我们讨论负责这种行为的机制。
Severe plastic deformation (SPD) of Cu, Ag and Nb ternary alloys with average Nb concentrations of 5, 10 and 15 at.% and an Ag concentration of 10 at.% was studied using high resolution scanning electron microscopy, atom probe tomography and X-ray diffraction. Ball-milled powders were compacted, annealed at 600 or 950 °C and subsequently strained by high pressure torsion at room temperature. Ag redistributed homogeneously in the Cu matrix during SPD, but the Nb solubility increased by less than 1%. The Nb precipitates, moreover, self-organized into a patterned microstructure, whereby their sizes all fell within a narrow distribution, centered on ∼20 nm. This size was independent of the initial microstructure for a given alloy and insensitive to the Nb concentration. The size was also insensitive to the method of shearing. Since Nb diffusion is negligible in Cu at room temperature, these results establish that SPD alone can induce compositional patterning in highly immiscible alloys. We discuss the mechanisms responsible for this behavior.