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建立了纳米晶合金相的热力学模型,可定量描述纳米尺度下合金体系中化合物相的热力学性质,并预测合金相的稳定性及其转变规律.利用该模型全面计算了纳米晶Sm-Co合金体系中各化合物相在不同晶粒尺寸下的摩尔吉布斯自由能随温度的变化关系,预测了纳米尺度下Sm-Co合金体系中各物相的相对稳定性及转变规律.模型预测结果示出,在室温附近,随着纳米晶粒尺寸的减小,某些纳米晶合金相的摩尔吉布斯自由能将由负值变为正值,预示着将向其他更稳定的纳米晶合金相转变,这是与传统粗晶材料中合金相的稳定性仅依赖于温度条件而完全不同的纳米晶合金体系的热力学特征.对实际制备的Sm-Co纳米晶合金体材料的相组成和相稳定性的测试结果证实了建立的纳米晶合金相热力学模型的正确性.
The thermodynamic model of the nanocrystalline alloy phase was established, which can describe the thermodynamic properties of the compound phase in the nanoscale and quantitatively predict the stability and transformation of the alloy phase. The nanocrystalline Sm-Co alloy system The relative Gibbs free energy of each compound phase at different grain sizes changes with the temperature to predict the relative stability and transformation rules of the phases in the Sm-Co alloy system at the nanoscale.The results of the model prediction show that , Near room temperature, as the size of the nanocrystalline grains decreases, the Gibbs free energy of some nanocrystalline alloy phases will change from negative to positive, indicating the transition to other more stable nanocrystalline alloys, This is the thermodynamic characteristics of the nanocrystalline alloy system which is totally different from the stability of the alloy phase in the conventional coarse-grained material only depending on the temperature condition. The phase composition and phase stability of the actually prepared Sm-Co nanocrystalline alloy material The test results confirm the correctness of the established thermodynamic model of nanocrystalline alloy phase.