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推导出了单相纳米晶合金的晶界过剩体积与晶粒尺寸之间的定量关系,建立了纳米晶合金的晶界热力学性质随温度和晶粒尺寸发生变化的确定性函数.针对SmCo_7纳米晶合金,通过纳米晶界热力学函数计算和分析,研究了单相纳米晶合金的晶粒组织热稳定性.研究表明,当纳米晶合金的晶粒尺寸小于对应于体系中品界自由能最大值的临界晶粒尺寸时,纳米晶组织处于相对稳定的热力学状态:当纳米晶粒尺寸达到和超过临界尺寸时,纳米晶组织将发生热力学失稳,导致不连续的快速晶粒长大.利用纳米晶合金热力学理论与元胞自动机算法相耦合的模型对SmCo7纳米晶合金在升温过程中的晶粒长大行为进行了计算机模拟,模拟结果与纳米晶合金热力学模型的计算预测结果一致,由此证实了关于纳米晶合金晶粒组织热稳定性的研究结论.
The quantitative relationship between the grain boundary excess grain size and grain size of single-phase nanocrystalline alloy was deduced, and the deterministic function of the grain boundary thermodynamics of nanocrystalline alloy with temperature and grain size was established. The thermal stability of single-phase nanocrystalline alloy was studied by the calculation and analysis of the thermodynamic function of the nanocrystalline boundary. The results show that when the grain size of nanocrystalline alloy is smaller than the maximum corresponding to the free energy in the system At the critical grain size, the nanocrystalline structure is in a relatively stable thermodynamic state: when the nanocrystalline grain size reaches and exceeds the critical size, the nanocrystalline structure will undergo thermodynamic instability, resulting in the discontinuous rapid grain growth.Using nanocrystalline The thermodynamics theory and the cellular automata algorithm are used to simulate the grain growth behavior of SmCo7 nanocrystalline alloy during the heating process. The simulation results are in good agreement with those of the nanocrystalline alloy thermodynamic model. The conclusions about the thermal stability of the nanocrystalline alloy grain structure.