A novel molecular dynamics approach to simulate micromechanical behavior in characteristic crystallographic planes of transparent alumina ceramics

JJ Chen and MQ Guo and SY Zhang and XY Wang and XM Zhu and ZH Song and ZQ Li, JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, 37, 3378-3387 (2025).

DOI: 10.1016/j.jmrt.2025.07.029

To investigate the anisotropic properties of brittle-prone transparent alumina ceramics (TACs) and guide the optimized design of material modification, this study employed a novel molecular dynamics (MD) approach to reproduce and analyze the anisotropic micromechanical behaviors of TACs during nanoindentation experiments, with a focus on industrially prevalent A-plane 11 2 0 and C-plane (0001) configurations (denoted as TACs-A and TACs-C, respectively). Nanoindentation experiments and morphological observations revealed distinct failure mechanisms: TACs-C exhibited preferential plastic failure characteristics (i.e., displacement pop-in events) during early indentation stages, whereas TACs-A demonstrated intense plasticity- dominated failure in mid-to-late stages due to superior hardness and elastic modulus, ultimately forming radial-intercrossed crack networks. The MD model incorporating the Embedded Atom Method (EAM) potential successfully replicated experimental phenomena. Critical findings include an HCP-to-FCC phase transformation of O atoms in TACs-A during indentation, dominated by Shockley 1/6<112> and Hirth 1/3<100> dislocations that impede slip motion, thereby enhancing mechanical properties and contributing to higher hardness/elastic modulus. Concurrently, dislocation analysis elucidated the early-stage displacement pop-in events in TACs-C: rapid dislocation proliferation (0-5 & Aring; penetration depth) induced localized stress concentration and abrupt displacement. Finally, two optimization strategies (doping modification and graphene atomic coating) were proposed, providing computational modeling support for TACs material design.

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