Uniaxial tension of crystalline CoSb3 with holes of different sizes: a molecular dynamics study

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2022, Vol.128 (1), Article 77
• Main Authors: Cai, Li-Ju, Yang, Xu-Qiu, Zhai, Peng-Cheng
• Format: Article
• Language: English
• Subjects: Applied physics; Characterization and Evaluation of Materials; Condensed Matter Physics; Crystal structure; Crystallinity; Crystallography; Dynamic structural analysis; Hole size; Machines; Manufacturing; Materials science; Mechanical analysis; Molecular dynamics; Nanotechnology; Optical and Electronic Materials; Optimization; Physics; Physics and Astronomy; Processes; Room temperature; Simulation; Single crystals; Stress concentration; Structural failure; Surfaces and Interfaces; Tensile stress; Thin Films; Ultimate tensile strength
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-021-05217-x

Breakthroughs in micro/nanostructural optimization have led to significant improvements in the thermoelectric performance of CoSb 3 -based skutterudites these years. With regard to the severe service condition and the practically defective structure of skutterudites, a comprehensive understanding of the mechanical reliability is needed. The present work carries out molecular dynamics simulations to study the mechanical response and structural failure of single-crystalline bulk CoSb 3 with nanoscale defect holes subjected to uniaxial tension along [100] crystallographic direction at room temperature. To focus on the variation of mechanical failure with the hole size, each simulation model contains only one cylindrical cavity of circular cross section. For different models, the hole diameter changes, but the hole ratio remains constant and small. The variation of tensile stress with strain is obtained from models of different hole diameters. It is possible to make a mathematical fitting from the decrease in ultimate strength with the diameter increase. Critical hole diameter can be predicted from the fitting function, beyond which the hole diameter does not play a role in the structure’s load capacity. The cause of strength degradation, stress concentration at the hole edge, is analyzed as well. The crack happens at different locations on the hole edge for each hole diameter model based on local atomic configuration and interactions. The uniaxial tension is also performed along [110] and [210] directions, respectively, and the results show remarkable orientation discrepancy. Our simulation results are compared with those of the classical theory of elasticity, which helps understand the variation of mechanical responses when the scale comes down to nanometer for CoSb 3 .