Role of columnar structure on the fracture anisotropy of physical vapor deposited Al/SiC nanolaminates

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:786

Article

Shen, Sijia¹  Chen, Yunsheng^2,4  Yang, Lingwei³  Feng, Yajie²  Xu, Jian² 

[1] Southwest Univ Sci & Technol, Sch Mat Sci & Engn, Mianyang 621000, Sichuan, Peoples R China

[2] Chinese Acad Sci, Engn Lab Adv Energy Mat, Ningbo Inst Mat Technol & Engn, Ningbo 315201, Peoples R China

[3] China Aerodynam Res & Dev Ctr, Hyperveloc Aerodynam Inst, Mianyang 621000, Sichuan, Peoples R China

[4] Univ Chinese Acad Sci, Beijing 100049, Peoples R China

关键词: Nanolaminates;    Mechanical property;    Micropillar compression;    Finite element model;   

DOI  :  10.1016/j.msea.2020.139387

来源: Elsevier

【 摘 要 】

In this work, the effect of layer thickness on the mechanical anisotropy of physical vapor deposited Al/SiC nanolaminate was explored by micropillar compressions at directions perpendicular (90 degrees) and parallel (0 degrees) to layer orientations. The role of inherent columnar structure on the fracture mechanism at both loading directions is highlighted. The results show that the Al/SiC micropillar compressed at 90 degrees was strengthened significantly as the layer thickness reduced, due to the constraint of Al plasticity (imposed by stiff SiC layers) and ruptures of SiC layers, both were layer thickness dependent. The constraint was weakened by the ruptures of SiC layers and the inherent columnar structures. Finite element modeling evidences that the latter may trigger early formations of shear bands crossing multiple layers, leading to decreased strain hardening rate and ultimate compressive strength of the Al/SiC micropillar. The strengthening effect was reversed at 0 degrees, with lower strength obtained in thinner layered micropillars. Finite element modeling of micropillar compression suggests that this is mainly a consequence of the inherent columnar structure that weakens remarkably the compressive strength.

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