Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys
Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys
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DOI：
10.1016/j.msea.2012.03.078
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发表时间：
2012-06-01
期刊：
影响因子：
6.4
通讯作者：
Averback, Robert S.
中科院分区：
文献类型：
--
作者：
Schaefer, Jonathan;Ashkenazy, Yinon;Averback, Robert S.
采用分子动力学模拟方法研究了稀相纳米晶合金(Cu-Nb、Cu-Fe、Cu-Zr)在高温下溶质偏析对热蠕变的影响。首次使用蒙特卡罗和分子动力学相结合的模拟技术来平衡分离溶质的分布。然后测量了稀铜样品的蠕变速率随温度、成分、载荷和累积应变的变化。在Cu-Nb样品中，蠕变速率最初随着应变的增加而增加，但随后在接近于通过在晶界随机定位溶质制备的合金中的蠕变速率时达到饱和。这一行为归因于晶界体积和能量的增加以及添加的化学无序。在高温下，蠕变的表观激活能异常高，为3 eV，但在较低温度下仅为0.3 eV。这种温度依赖关系被发现与大块Cu-Nb玻璃中的原子迁移率有关。对含有其他溶质Fe和Zr的纳米晶铜合金的蠕变计算表明，当合金溶解在铜中时，蠕变速率的抑制程度与其原子体积成比例。(C)2012爱思唯尔B.V.保留所有权利。
The effect of solute segregation on thermal creep in dilute nanocrystalline alloys (Cu-Nb, Cu-Fe, Cu-Zr) was studied at elevated temperatures using molecular dynamics simulations. A combined Monte-Carlo and molecular dynamics simulation technique was first used to equilibrate the distribution of segregating solutes. Then the creep rates of the diluted Cu samples were measured as functions of temperature, composition, load and accumulated strain. In Cu-Nb samples, the creep rates were observed to increase initially with strain, but then saturate at a value close to that obtained for alloys prepared by randomly locating the solute in the grain boundaries. This behavior is attributed to an increase in grain boundary volume and energy with added chemical disorder. At high temperatures, the apparent activation energy for creep was anomalously high, 3 eV, but only 0.3 eV at lower temperatures. This temperature dependence is found to correlate with atomic mobilities in bulk Cu-Nb glasses. Calculations of creep in nanocrystalline Cu alloys containing other solutes, Fe and Zr, show that the suppression of creep rate scales with their atomic volumes when dissolved in Cu. (C) 2012 Elsevier B.V. All rights reserved.