Thermodynamic properties of Al, Ni, NiAl, and Ni3Al from first-principles calculations
Thermodynamic properties of Al, Ni, NiAl, and Ni3Al from first-principles calculations
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DOI：
10.1016/j.actamat.2004.02.014
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发表时间：
2004-05
期刊：
影响因子：
9.4
通讯作者：
Y. Wang;Zi-kui Liu;Long-Qing Chen
中科院分区：
文献类型：
--
作者：
Y. Wang;Zi-kui Liu;Long-Qing Chen
用第一性原理方法研究了Al、Ni、NiAl和Ni3Al的热力学性质。在广义梯度近似下，用从头算平面波赝势方法计算了0-K总能量。利用从头算线性响应理论得到的声子态密度，计算了晶格振动对自由能的贡献。通过对电子态密度的一维数值积分，得到了热电子对自由能的贡献。利用推导出的亥姆霍兹自由能，计算了热膨胀和热焓随温度的变化，并与实验数据进行了比较。计算结果表明，NiAl和Ni3Al的生成热与温度关系不大，斜率分别为−1.6J/m o l/K和−1.2J/m o l/K。对于Ni，在1600K时，热电子激发的引入使其热膨胀增加10%，热焓增加15%。
The thermodynamic properties of Al, Ni, NiAl, and Ni3Al were studied using the first-principles approach. The 0-K total energies are calculated using the ab initio plane wave pseudopotential method within the generalized gradient approximation. The contribution to the free energy from the lattice vibration was calculated using the phonon densities of states derived by means of the ab initio linear-response theory. The thermal electronic contribution to the free energy was obtained from the one-dimensional numerical integration over the electronic density of states. With the deduced Helmholtz free-energy, the thermal expansion and enthalpy as a function of temperature were calculated and compared with the experimental data. Our calculations show that the enthalpies of formation are slightly temperature dependent with a slope of −1.6 J/mol/K for NiAl and −1.2 J/mol/K for Ni3Al. For Ni, the inclusion of thermal electronic excitation results in a 10% increase in thermal expansion and 15% increase in enthalpy at 1600 K.