Phase stability in nanocrystalline metals: A thermodynamic consideration
Phase stability in nanocrystalline metals: A thermodynamic consideration
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DOI：
10.1063/1.2822473
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发表时间：
2007-12
影响因子：
3.2
通讯作者：
W. Qin;T. Nagase;Y. Umakoshi
中科院分区：
文献类型：
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作者：
W. Qin;T. Nagase;Y. Umakoshi
从热力学角度研究了金属纳米晶结构转变的机理。晶格畸变和界面效应是导致结构不稳定的原因。采用球磨法和晶化法制备了纳米晶Fe样品，并进行了分析比较。分别采用准谐德拜近似和Gibbs-Thomson方程计算了晶格畸变和界面能对热力学的贡献。通过考察吉布斯自由能的变化，并考虑晶界负应力对结构转变中晶体体积变化的影响，计算了fcc-Fe形成的临界晶粒尺寸。结果表明，相对于晶化纳米晶状态，球磨纳米晶状态更容易形成面心立方结构的铁。纳米晶材料中是否发生相变与其制备工艺密切相关。
The mechanism of structural transition in nanocrystalline metals was studied from a thermodynamic point of view. Crystal lattice distortion and interfacial effect were found to be the reasons for structural instability. Nanocrystalline Fe samples prepared by the milling method and by the crystallization method were used for analyses and comparison. The contributions of lattice distortion and interfacial energy to thermodynamics were calculated using the quasiharmonic Debye approximation and the Gibbs-Thomson equation, respectively. By examining the change in Gibbs free energy and considering the effect of negative stress of grain boundaries on the crystal volume change in structural transition, we calculated the critical grain size of fcc-Fe formation. Results show that relative to the crystallized nanocrystalline state, it is more likely that the fcc Fe forms in the milled nanocrystalline state. Whether or not the phase transition occurs in nanocrystalline materials is closely related to the preparation ...