Unraveling the Role of Grain Boundary Anisotropy in Sintering: Implications for Nanoscale Manufacturing
Unraveling the Role of Grain Boundary Anisotropy in Sintering: Implications for Nanoscale Manufacturing
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DOI：
10.1021/acsanm.1c01322
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发表时间：
2021-07-19
影响因子：
5.9
通讯作者：
Abdeljawad, Fadi
中科院分区：
文献类型：
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作者：
Hussein, Omar;Alghalayini, Maher;Abdeljawad, Fadi
烧结是一种热加工技术，用于将颗粒压块固结成广泛用于光学、催化、电子和结构应用的结构。特别令人感兴趣的是纳米晶体颗粒的烧结，因为它导致降低的烧结温度和更快的加工时间，并且它能够制造块状纳米结构或纳米多孔材料。然而，缺乏知识的晶界（GB）的几何形状在烧结速率的作用限制了我们的能力，操纵致密化和粗化过程。在这里，我们利用原子模拟研究烧结行为的一系列[001]倾斜GB在镍超过200纳秒使用两个粒子的几何形状。计算这些GB的能量和自扩散，并跟踪随着时间的推移描述的形态演变的几个几何特征。粒子旋转，导致在时间上的演变GB的取向差，观察到在几个系统。我们的研究结果表明，作为GB类型的函数，颗粒颈部的生长和收缩率的变化很大，并建议更快的烧结速率与GB取向差角的增加。此外，它被发现，纳米粒子烧结的速度比从GB为基础的烧结模型预测慢得多，这表明该过程是不是由一个单一的机制为主。作为烧结应力的测量，我们跟踪粒子颈部曲率的时间演变，这表明随着时间的推移，以取决于GB几何形状的速率降低。从广义上讲，我们的模拟结果提供了未来的途径，采用颗粒取向和由此产生的GB类型作为一种策略，以制造烧结材料与控制纳米结构的功能。
Sintering is a thermal processing technique used to consolidate particle compacts into structures broadly used in optical, catalytic, electronic, and structural applications. Of particular interest is the sintering of nanocrystalline particles, as it leads to reduced sintering temperatures and faster processing times and it enables the fabrication of bulk nanostructured or nanoporous materials. However, the lack of knowledge of the role of grain boundary (GB) geometry in sintering rates limits our ability to manipulate densification and coarsening processes. Herein, we leverage atomistic simulations to investigate the sintering behavior of a series of [001] tilt GBs in Ni over 200 ns using the two-particle geometry. The energy and self-diffusion for these GBs are calculated, and several geometric features describing the morphological evolution are tracked over time. Particle rotation, resulting in the temporal evolution of GB misorientation, is observed in several systems. Our results show large variations in particle neck growth and shrinkage rates as a function of GB type and suggest faster sintering rates with increased GB misorientation angle. Further, it is found that nanoparticles sinter at a much slower rate than predicted from GB-based sintering models, suggesting that the process is not dominated by a single mechanism. As a measure of sintering stress, we track the temporal evolution of particle neck curvatures, which are shown to decrease over time at a rate dependent on GB geometry. In broad terms, our simulation results provide future avenues to employ particle orientations and resultant GB types as a strategy to fabricate sintered materials with controlled nanostructured features.