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在纳米结构的金属及合金中,随着晶粒尺寸的下降,晶界体积分数显著增加,使得晶粒长大的驱动力提高,因此纳米金属在加热时(甚至是室温下)是不稳定的,限制了其加工与应用。本文对Trelewicz/Schuh(TS)模型进行了修正,并利用修正的模型对Cu-6.5at%Zr、Cu-6.5at%Nb纳米晶合金的热力学稳定倾向进行了计算研究。实验利用机械合金化的方法制备这两种纳米晶合金,并在不同温度下进行退火。实验结果及理论计算表明,随着溶质原子的加入及在晶界的偏聚,这两种纳米晶合金的晶粒长大得到抑制,热力学稳定性提高。
In nanostructured metals and alloys, as the grain size decreases, the grain-boundary volume fraction increases significantly, driving the growth of the grains so that the nanometal is unstable on heating (even at room temperature) , Limits its processing and application. In this paper, the model of Trelewicz / Schuh (TS) is modified, and the thermodynamic stability tendency of Cu-6.5at% Zr and Cu-6.5at% Nb nanocrystalline alloys is calculated by the modified model. In the experiment, the two kinds of nanocrystalline alloys were prepared by mechanical alloying and annealed at different temperatures. The experimental results and theoretical calculations show that with the addition of solute atoms and segregation at the grain boundaries, the grain growth of the two nanocrystalline alloys is inhibited and the thermodynamic stability is improved.