非简谐振动对Fe_1-xCo_xSi合金热力学性质的影响
Influence of Anharmonic Vibration on the Thermomechanical Properties of Fe_1-xCo_xSi Alloy

建立Fe_1-xCo_xSi合金的物理模型，应用热力学和固体物理理论，得到系统的吉布斯函数和自由能以及德拜温度、弹性模量、热容量随温度变化的解析式，探讨了非简谐效应以及杂质浓度对Fe_1-xCo_xSi合金热力学性质的影响.结果表明：①合金Fe_1-xCo_xSi的德拜温度和弹性模量均随温度升高而减小，但变化非常缓慢，而定压热容量随温度升高而非线性地增大，其中温度较低时，近似遵从T³次方定律；② Fe_1-xCo_xSi的德拜温度、弹性模量、定压热容量以及非简谐项对热容量的影响均随含钴杂质浓度的增加而增大；③若不考虑原子的非简谐振动，则合金的德拜温度和弹性模量为常量.在考虑到原子非简谐效应项后，则随温度变化而变化.温度愈高，杂质浓度和非简谐振动对合金热力学性质的影响愈显著.
In a study reported herein, a physical model of the Fe_1-xCo_xSi alloy was established. Applying the theory of thermodynamics and solid state physics, the physical model's Gibbs function, free energy, Debye temperature, elastic modulus and analytical formula of heat capacity varying with temperature change were obtained. In addition, the effects of anharmonic vibration and impurity concentration on the thermodynamic properties of Fe_1-xCo_xSi alloy were discussed. The results were as follows. (1) With increasing temperature, the Debye temperature and elastic modulus of the alloy slowly decreased, but the constant pressure heat capacity non-linearly increased, which approximately obeyed the T3 law of the second on the condition that the temperature was low. (2) The effects of its Debye temperature, elastic modulus, constant pressure heat capacity and anharmonic vibration on heat capacity all increased with the increase in the impurity concentration of cobalt. (3) Without considering atomic anharmonic vibration, the Debye temperature and elastic modulus of the alloy were constant. In contrast, when atomic anharmonic vibration was taken into consideration, the Debye temperature and elastic modulus of the alloy would vary with the temperature, and the results showed that the influence of impurity concentration and anharmonic vibration on the thermodynamic properties of the alloy became more significant when temperature was higher