Nucleation controlled reaction of Cu3Si in the field of sharp concentration gradient
Nucleation controlled reaction of Cu3Si in the field of sharp concentration gradient
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DOI：
10.1016/j.actamat.2016.04.041
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发表时间：
2016-06-15
期刊：
影响因子：
9.4
通讯作者：
Schmitz, G.
中科院分区：
文献类型：
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作者：
Ibrahim, M.;Balogh-Michels, Z.;Schmitz, G.
金属间化合物在急剧浓度梯度场的形成具有复杂的热力学驱动力和动力学约束。我们用互补的高分辨方法（APT， HR-TEM和XRD）比较了Cu3Si在渐变界面和突变界面的形成。逐渐的转变导致在沉积过程中立即形成非晶间层。这使得Cu3Si晶体的成核屏障几乎为零。然而，在突变的情况下，相的形成被延迟。首先必须形成一种中间混合物。这可以发生在界面的Cu一侧，但Si向Cu的扩散是缓慢的。因此，还观察到另一种途径：1)Si对Cu晶界的润湿。Cu非均相渗透到a-Si基体中的应力松弛。3)。a-Si中Cu析出物的形成。4) Si溶入纯Cu析出物。5) Cu （Si）析出相转变为化学计量Cu3Si层。这些发现与传统观点相反，即第一硅化物相总是独立形成核。(C) 2016材料学报Elsevier Ltd.出版。版权所有。
Formation of intermetallic compounds in the field of a sharp concentration gradient has complicated thermodynamic driving forces and kinetic constraints. We have compared the formation of Cu3Si at a gradual interface to that at an abrupt one by complementary high resolution methods (APT, HR-TEM and XRD). The gradual transition leads to the immediate formation of an amorphous interlayer during deposition. This reduces the nucleation barrier for the crystalline Cu3Si to practically nil. However, in the case of the abrupt transition, phase formation is delayed. First an intermediate mixture must be formed. This can happen at the Cu side of the interface, but the diffusion of Si into Cu is slow. Therefore, an alternative route is also observed: 1) Wetting of Cu grain boundaries by Si. 2.) Stress relaxation by heterogeneous penetration of Cu into the a-Si matrix. 3.) Formation of Cu precipitates in a-Si. 4) Dissolution of Si into the pure Cu precipitates. 5) Transformation of Cu (Si) precipitates into stoichiometric Cu3Si layer. These findings contrast with the traditional view that the first silicide phase always forms nucleation-independently. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.