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arXiv 1202.3068cond-mat.mtrl-sciphysics.comp-ph
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用改进的嵌入原子方法计算铁(Fe $_3$ C)的结构、弹性和热学性质

Structural, elastic and thermal properties of cementite (Fe$_3$C) calculated using Modified Embedded Atom Method

Laalitha S. I. Liyanage, Jeff Houze, Sungho Kim, Mark A. Tschopp, Seong-Gon Kim, Michael I. Baskes, Mark F. Horstemeyer

摘要:

采用改进的嵌入原子法(MEAM)势研究了铁碳(Fe-C)合金的结构、弹性和热性能。使用先前开发的Fe和C单元素势来开发Fe-C合金MEAM势,使用基于热力学的优化方案来再现Al 2 O3的结构和弹性性质、bcc Fe中C的间隙能以及L $_{12}$和B $_1$结构中Fe-C合金的形成热。采用分子动力学模拟研究了高温下铁电体的稳定性。通过计算应变胞元的总能量,得到了碲镉汞的9个单晶弹性常数。从多晶弹性常数出发,计算了多晶弹性模量。同时计算了菱铁矿(001)、(010)和(100)面的形成能。采用固/液两相分子动力学模拟研究了碳酸镁的熔化温度、比热容和体积随温度的变化规律。势的预测与第一性原理计算和实验符合得很好。

英文摘要:

Structural, elastic and thermal properties of cementite (Fe$_3$C) were studied using a Modified Embedded Atom Method (MEAM) potential for iron-carbon (Fe-C) alloys. Previously developed Fe and C single element potentials were used to develop an Fe-C alloy MEAM potential, using a statistically-based optimization scheme to reproduce structural and elastic properties of cementite, the interstitial energies of C in bcc Fe as well as heat of formation of Fe-C alloys in L$_{12}$ and B$_1$ structures. The stability of cementite was investigated by molecular dynamics simulations at high temperatures. The nine single crystal elastic constants for cementite were obtained by computing total energies for strained cells. Polycrystalline elastic moduli for cementite were calculated from the single crystal elastic constants of cementite. The formation energies of (001), (010), and (100) surfaces of cementite were also calculated. The melting temperature and the variation of specific heat and volume with respect to temperature were investigated by performing a two-phase (solid/liquid) molecular dynamics simulation of cementite. The predictions of the potential are in good agreement with first-principles calculations and experiments.

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