Atomic-level understanding of materials provides elemental insights into structure and properties of crystalline defects and surface. It is also a path to describe physical mechanisms of many processes ranging from atomic diffusion to interface migration. Input parameters provided by atomistic models serve as a guide for the development of continuum models at meso-scale and macroscale [1]. On the other hand difficulties in a description of structurally complex materials arise from the complexity of local atom network due to the presence of discontinuity in long-range order due to the presence of defects, crystal imperfections.

Herein we present structure and topology of various interface in fcc material by using Voronoi tessellation based method (Voronoi analysis, VA) [2] and Order parameter (OP) approach [3]. We have performed molecular dynamics simulation at selected temperatures for both external and internal interfaces of aluminium containing materials, including surfaces and grain boundaries. Functionality of the VA method is presented and discussed with structural analysis based on order parameter (OP) approach to scrutinize structure of both GB and surface, its structural order in nanocrystalline aluminum based system [4]. Sensitivity of the VA method enables to capture small atom rearrangements around grain boundary or surface and give new insights into the presence of lattice distortions, which can organize into loop-like structures or result in liquid-like GB behavior. The OP approach is less sensitive to the nature and type of features occurring within GB structure but gives results which are compatible with changes captured by the VA method.

Our present studies demonstrate a possibility for identification and description of structurally complex materials [4,5], which will allow us for getting deeper into structure and topology of GB and surface changes in the grain bulk induced by GB and other irregularities. The methods used herein can also be useful for describing diffusion, mobility as well as complexion transformation of GB which will be discussed in our further work. Two complementary methods used in this work provide new information and open new possibilities for studying structure and properties of nanomaterials.

Acknowledgments:
The presented results were obtained using computational resources provided through PLGrid Infrastructure at Academic Computer Centre Cyfronet AGH. The Authors are grateful for financial support provided by National Science Centre in Poland through Grant No: 2016/21/D/ST8/01689 and project No 2018/29/B/ST8/02558.

References:
[1] Y. Mishin, M. Asta, Ju Li, Acta Mater. 58 (4) (2010) 1117–1151
[2] A. Stukowski, Model. Simul. Mater. Sci. Eng. 20 (2012) 045021
[3] K.G.F. Janssens, et al., Nat. Mater. 5 (2) (2006) 124–127
[4] A. Żydek, M. Wermiński, M.E. Trybula, Comput Mater Sci 197, (2021), 110660
[5] A. Drewienkiewicz, A. Zydek, M.E.Trybula and J. Pstruś, Nanomaterials, 11(6), 2021, 1465