电场对铝基材料能量参数的电子层面计算研究

【作者】 张建军；

【导师】 陈铮；

【作者基本信息】 西北工业大学 ， 材料学， 2004， 硕士

【摘要】 本文以铜、锂、铝单原子以及铝基化合物、固溶体、合金为客体，首次推导出了电场下的能量参数的计算方法，系统地定量计算研究了电场下的能量、压强、自由能、吉氏自由能、熵等能量参数。 基于Thomas—Fermi方程，推导出了单原子的熵、自由能、吉氏自由能的计算方法。在此基础上，遵循平均原子模型的要求，应用体积相加法，循环叠代的打靶法，将此方法推广到化合物、固溶体、合金。同时，确定了电场下的内势场边界条件，建立了电场下单原子、化合物、固溶体、合金的能量参数计算方法。 针对单原子、化合物、固溶体、合金，发现了能量、压强、自由能、吉氏自由能、熵等能量参数随外电场的变化均呈曲线形式，并且在极值区域附近能量参数都有升高和降低的振荡，存在两极小值点，极值区域、极大值、极小值均因温度不同而异。得出了能量参数曲线对正负电场的对称规律，铜、锂、铝等单原子呈非零点对称：Al-2.14wt.％Li固溶体呈近似零点对称；Al₃Li化合物在800K呈非零点对称，460K时呈近似零点对称；1420铝锂合金、2090铝锂合金及LY12铝合金，两种温度下都是呈近似零点对称的，460K时，正电场中的极小值要高于负电场中的极小值。 铜原子的能量参数对电场的作用最敏感，铝、锂次之；Al₃Li化合物在460K的能量值明显的低于800K的能量值，同时，低于Al-2.14wt.％Li固溶体460K时的能量值。更多还原

【Abstract】 In this paper, the calculation method of the energy parameter for coppers, lithium, aluminum monatomic and compound, solid solution, alloy based on aluminum were derived out under the electric field for the first time. The energy parameters such as energy, pressure, Helmholtz free energy, Gibbs free energy and entropy under the electric field were calculated and studied systematically.Based on Thomas-Fermi equation, the calculation methods of the monatomic entropy, Helmholtz free energy, Gibbs free energy were driven out. On the basis of these, following the requests of the average atom model, using volume adding method and circulation target-shooting method, the calculating methods have been extended to the case of compound, solid solution, and alloy. Besides, the interior potential boundary condition under the electric field has been defined. Energy parameters calculation methods of monatomic, compound, solid solution, and alloy under the electric field have been set up.Energy parameters, such as energy, pressure, Helmholtz free energy, Gibbs free energy and entropy, which present the curve form with the change of the electric field have been found to the monatomic, compound, solid solution, and alloy. Energy parameters vibrated near the area of the extreme value, two minimum and some exists. The locations of extreme value, maximum, minimum were different when temperature was different. The symmetrical law of the energy parameter curves under positive and negative electric field has been driven out. Copper, lithium, aluminum monatomic present that zero point is not symmetrical, Al-2.14wt.%Li solid solution present that it is approximate to the zero point symmetry, AI3U compound present that the zero point is not symmetry when the temperature is 800K,and it is approximate to the zero point symmetrically when the temperature is 460K.1420 Al-Li alloy,2090 Al-Li alloy and LY12 aluminum alloy, are approximate to the zero point symmetry at the both temperatures. At 460K, minimums of the positive electric field are higher than minimum of negative electric field.Energy parameter of copper atom under electric field is the most sensitive function, aluminum, lithium take the second place. At 460K, the energy parameter values of AI3Li compound are obviously lower than that at 800K and that of Al-2.14wt.%Li solid solution at 460K.更多还原