Crack and its interaction with defects in Al coated with Cu 50 Zr 50 metallic glass thin film: an MD simulation study
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ORIGINAL PAPER
Crack and its interaction with defects in Al coated with Cu50Zr50 metallic glass thin film: an MD simulation study Pradeep Gupta 1 & Krishna Chaitanya Katakam 1 & Ganesh Katakareddi 1 & Natraj Yedla 1 Received: 16 April 2019 / Accepted: 26 February 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Molecular dynamics (MD) simulation studies are carried out to investigate the crack propagation behavior and crack-void interactions in Al coated with Cu50Zr50 metallic glass (MG) thin film model. The model thin film is subjected to mode I and mode II loading conditions at a temperature of 300 K and a strain rate of 1010 s−1. The simulations are carried out in the framework of EAM (embedded atom method) potential based on the CZM (cohesive zone model). The model size is 435 Å (x-axis) × 174 Å (y-axis) × 17 Å (z-axis). Nine models are investigated containing an edge crack (length, L = 43 Å, and 118 Å) located at the interface and voids (diameter, ϕ = 10–36 Å) located in the Al region and at the interface. The results show that crack propagation occurs by dislocation emission and blunts the crack tip. The presence of void ahead of the crack tip restricts the crack propagation due to the stress field resulting in bowing out of the crack and is effective with an increase in the void size which grows normal and parallel to the loading direction. The estimated crack speeds in mode I and mode II are 366 m/s and 370 m/s during stable crack growth. Separation of the interface occurs by fracture of the ligaments between the voids. Shockley partial dislocations are found nucleating from the void surfaces; twinned regions are found between the voids. The work of separation is found to be 11.56 J/m2 for mode I and 3.7 J/m2 in mode II, indicating that failure occurs in mode II. Keywords Molecular dynamics . Interface . Voids . Mode I . Mode II . Crack speed
Introduction The presence of second phase inclusions can either improve the toughness or decrease the toughness [1] of the matrix, thereby affecting the fracture properties. Valuable insight into the crackinclusion interactions and strength of the interface is essential to understand the fracture behavior. Over the years, some studies have reported on the crack-inclusion interactions from nanoscale to macro-scale [2–4]. The several factors that affect the crack propagation behavior are shape, size, and positions of the crack and inclusion [3, 4]. Further, the presence of inclusion alters the stress distribution around the crack and may amplify or reduce (shielding) the stress intensity factor [4]. The shielding effect can also be caused due to the dislocation nucleation at the crack tip [5, 6]. Liu and Groh [7] molecular
* Natraj Yedla [email protected] 1
Computational Materials Engineering Group, Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008, India
dynamics (MD) simulation studies on the interaction between crack and void in α-Fe suggest that crack growth is faster at a temper
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