PSI - Issue 35

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ScienceDirect

Procedia Structural Integrity 35 (2022) 261–268 Structural Integrity Procedia 00 (2021) 000–000 Structural Integrity Procedia 00 (2021) 000–000

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© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalçinkaya Abstract Bulk Metallic Glasses (BMGs) exhibit superior mechanical properties such as high strength ( ≈ 2 GPa), high yield strain ( ≈ 2%) and high corrosion resistance. But, they lack ductility which prevents them from being used as structural materials. One of the methods explored by material scientists to improve their strain to failure is to coat BMGs with a thin layer of a ductile polycrystalline metal such as Copper. In this work, we numerically investigate the mechanical behavior of thin film coated BMGs through Finite Element (FE) Simulations. We simulate the e ff ect of an extrinsic copper coating on the deformation and failure of monolithic BMG cylinders under uniaxial loading. We employ the Anand and Su (2005) constitutive model for BMGs implemented by us in ABAQUS FE software via user material subroutines: UMAT and VUMAT. An isotropic, elastoplastic material model is used for representing the Copper coating with properties of pure Copper. Three-dimensional, two-dimensional plane strain and axisymmetric simulations of uniaxial loading of monolithic BMG and Copper coated BMG composite at quasi-static strain-rate are performed using the Explicit / Dynamics formulation in ABAQUS. The simulations take into consideration a ductile damage and failure mechanism involving cracking inside the shear bands in the BMG matrix. We observe the formation of shear bands which transform into cracks in the BMG matrix. The simulations are able to correctly predict the deformation and fracture mechanism of the BMG matrix and copper coating under uniaxial loading. Results show that a thin copper coating of about 1–5% of the diametrical thickness of the cylinder increases the strain to failure of the coated BMG composite by about 2% which is in qualitative agreement with experimental observations reported in literature. The present results have implications for designing coated BMGs with improved malleability or strain to failure enabling their deployment in structural applications. 2021 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http: // cr ativec mmons.org / licenses / by-nc-nd / 4.0 / ) r-review unde responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya. Keywords: Bulk Metallic Glass (BMG); copper coating; shear bands; fracture; damage model 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials echanics of thin film coated Bulk etallic Glass composites Onkar Salunkhe a, ∗ , Parag Tandaiya a a Department of Mechanical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai – 400076, India Abstract Bulk Metallic Glasses (BMGs) exhibit superior mechanical properties such as high strength ( ≈ 2 GPa), high yield strain ( ≈ 2%) and high corrosion resistance. But, they lack ductility which prevents them from being used as structural materials. One of the methods explored by material scientists to improve their strain to failure is to coat BMGs with a thin layer of a ductile polycrystalline metal such as Copper. In this work, we numerically investigate the mechanical behavior of thin film coated BMGs through Finite Element (FE) Simulations. We simulate the e ff ect of an extrinsic copper coating on the deformation and failure of monolithic BMG cylinders under uniaxial loading. We employ the Anand and Su (2005) constitutive model for BMGs implemented by us in ABAQUS FE software via user material subroutines: UMAT and VUMAT. An isotropic, elastoplastic material model is used for representing the Copper coating with properties of pure Copper. Three-dimensional, two-dimensional plane strain and axisymmetric simulations of uniaxial loading of monolithic BMG and Copper coated BMG composite at quasi-static strain-rate are performed using the Explicit / Dynamics formulation in ABAQUS. The simulations take into consideration a ductile damage and failure mechanism involving cracking inside the shear bands in the BMG matrix. We observe the formation of shear bands which transform into cracks in the BMG matrix. The simulations are able to correctly predict the deformation and fracture mechanism of the BMG matrix and copper coating under uniaxial loading. Results show that a thin copper coating of about 1–5% of the diametrical thickness of the cylinder increases the strain to failure of the coated BMG composite by about 2% which is in qualitative agreement with experimental observations reported in literature. The present results have implications for designing coated BMGs with improved malleability or strain to failure enabling their deployment in structural applications. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya. Keywords: Bulk Metallic Glass (BMG); copper coating; shear bands; fracture; damage model 2nd International Workshop on Plasticity, Damage and Fracture of Engineering Materials Mechanics of thin film coated Bulk Metallic Glass composites Onkar Salunkhe a, ∗ , Parag Tandaiya a a Department of Mechanical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai – 400076, India

1. Introduction 1. Introduction

Metallic glasses are super-cooled alloys prepared by cooling metallic liquid at a very high rate of cooling to avoid crystallization. The first metallic glass Au 75 Si 25 was synthesized by Jun. et al. (1960). They used rapid quenching techniques for cooling the metallic liquid at very high rates of around 10 5 –10 6 K / s. The use of high cooling rates prevents crystallization. Subsequently, in the 1990s, certain multicomponent alloys were processed in amorphous Metallic glasses are super-cooled alloys prepared by cooling metallic liquid at a very high rate of cooling to avoid crystallization. The first metallic glass Au 75 Si 25 was synthesized by Jun. et al. (1960). They used rapid quenching techniques for cooling the metallic liquid at very high rates of around 10 5 –10 6 K / s. The use of high cooling rates prevents crystallization. Subsequently, in the 1990s, certain multicomponent alloys were processed in amorphous

∗ Corresponding author. Onkar Salunkhe Tel.: + 1 9063707294 E-mail address: nkrsalunkhe@gmail.com ∗ Corresponding author. Onkar Salunkhe Tel.: + 1 9063707294 E-mail address: nkrsalunkhe@gmail.com

2452-3216 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yal ç inkaya 10.1016/j.prostr.2021.12.073 2210-7843 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review u der responsibility of IWPDF 2021 hair, Tu cay Yalc¸inkaya. 2210-7843 © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalc¸inkaya.