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建立了纳米晶合金的热力学性质随温度和晶粒尺寸变化的函数关系。通过计算分析了Li2C2纳米晶合金的吉布斯自由能随温度和晶粒尺寸的变化,研究了其相稳定性和相变特征。模型预测结果显示,当晶粒尺寸减小到100 nm以下时,相变温度均低于粗晶块体材料的相变温度,且随晶粒尺寸的减小而进一步降低。在室温下(300 K),当晶粒尺寸减小至约6 nm及以下时,传统高温稳定相β-Li2C2相可以在室温下稳定存在。
The thermodynamic properties of nanocrystalline alloys were established as a function of temperature and grain size. The Gibbs free energies of Li2C2 nanocrystalline alloys were calculated and analyzed for their phase stability and phase transition characteristics with temperature and grain size. The model predictions show that when the grain size decreases below 100 nm, the phase transition temperature is lower than the phase transition temperature of the bulk material and decreases further with the decrease of the grain size. At room temperature (300 K), the β-Li2C2 phase of the traditional high temperature stable phase can be stably present at room temperature when the grain size is reduced to about 6 nm and below.