Olsson Pär A T, Awala Ibrahim, Holmberg-Kasa Jacob, Krause Andreas M, Tidefelt Mattias, Vigstrand Oscar, Music Denis
Materials Science and Applied Mathematics, Malmö University, SE-205 06 Malmö, Sweden.
Division of Mechanics, Materials and Components, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden.
Materials (Basel). 2023 Jul 16;16(14):5032. doi: 10.3390/ma16145032.
In the present work, we have used classical molecular dynamics and quantum mechanical density functional theory modeling to investigate the grain size-dependent thermal expansion coefficient (CTE) of nanocrystalline Cu. We find that the CTE increases by up to 20% with a gradually decreasing grain size. This behavior emerges as a result of the increased population of occupied anti-bonding states and bond order variation in the grain boundary regions, which contribute to the reduced resistance against thermally-induced bond stretching and dictate the thermal expansion behavior in the small grain size limit. As a part of the present work, we have established a procedure to produce ab initio thermal expansion maps that can be used for the prediction of the grain size-dependent CTE. This can serve as a modeling tool, e.g., to explore the impact of grain boundary impurity segregation on the CTE.
在本研究中，我们使用经典分子动力学和量子力学密度泛函理论建模来研究纳米晶铜的晶粒尺寸依赖性热膨胀系数（CTE）。我们发现，随着晶粒尺寸逐渐减小，CTE增加了高达20%。这种行为的出现是由于晶界区域中占据的反键态数量增加和键序变化，这导致了对热诱导键拉伸的阻力降低，并决定了小晶粒尺寸极限下的热膨胀行为。作为本研究的一部分，我们建立了一种程序来生成从头算热膨胀图，该图可用于预测晶粒尺寸依赖性CTE。这可以作为一种建模工具，例如，用于探索晶界杂质偏析对CTE的影响。
