Achieving maximum hardness in semi-coherent multilayer thin films with unequal layer thickness
Achieving maximum hardness in semi-coherent multilayer thin films with unequal layer thickness
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DOI：
10.1016/j.actamat.2012.01.029
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发表时间：
2012-04-01
期刊：
影响因子：
9.4
通讯作者：
Anderson, Peter M.
中科院分区：
文献类型：
--
作者：
Carpenter, John S.;Misra, Amit;Anderson, Peter M.
通过测量不同双层周期（λ）和Ni体积分数（% Ni）的Cu/Ni多层膜的面内晶格参数和硬度（H），研究了[001]外延Cu/Ni多层膜中塑性强化的来源。类似于其他的调查，H为50%Ni-50%Cu膜的双层周期下降到λ = 20 nm，其中界面是连贯的，随着减少而增加。一个新的发现是，H半相干薄膜增加% Ni。该策略产生了该系统的最大报告H（对于60%Ni/40%Cu为5.2GPa，λ = 60 nm），表明较小并不总是较强。增加的H的理由是在弹塑性过渡到完全塑性屈服期间大的界面位错密度的发展。这加强了Cu/Ni界面的滑移传播。结果解释与位错为基础的模型，估计的界面位错线能量，钉扎强度限制层滑移，和界面势垒强度滑移传输。(C)2012 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Sources of plastic strengthening in [001] epitaxial Cu/Ni multilayer thin films are examined using measurements of in-plane lattice parameter and hardness (H) for films of different bilayer period (Lambda) and Ni volume fraction (% Ni). Similar to other investigations, H for 50% Ni-50% Cu films increases with decreasing bilayer period down to Lambda = 20 nm, where interfaces are coherent. A new finding is that H for semi-coherent films increases with % Ni. This strategy yields the largest reported H for this system (5.2 GPa for 60% Ni/40% Cu, Lambda = 60 nm), showing that smaller is not always stronger. The rationale for the increased H is the development of a large interfacial dislocation density during the elasto-plastic transition to fully plastic yield. This strengthens Cu/Ni interfaces to slip propagation. The results are interpreted with a dislocation-based model that furnishes estimates of interfacial dislocation line energies, pinning strengths to confined layer slip, and interface barrier strengths to slip transmission. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.