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Issue 17, 2021
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Deformation mechanisms of Inconel-718 at the nanoscale by molecular dynamics

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Abstract

Ni-based super alloy Inconel-718 is ubiquitous in metal 3D printing where a high cooling rate and thermal gradient are present. These manufacturing conditions are conducive to high initial dislocation density and porosity or voids in the material. This work proposes a molecular dynamics (MD) analysis method that can examine the role of dislocations, cooling rates, voids, and their interactions governing the material properties and failure mechanisms in Inconel-718 using the Embedded Atom Method (EAM) potential. Throughout this work, three different structures – nanowires (NWs), nanopillars (NPs), and thin-plates – are used. The strain rate is varied from 108 s−1 to 1010 s−1 and the temperature is varied from 100 K to 800 K. Different cooling rates ranging from 0.5 × 1010 K s−1 to 1 × 1014 K s−1 are applied. Our results suggest that the high cooling rates create regular crystalline structures which result in high strength and ductility. In contrast, the lower cooling rates form a non-crystalline structure that exhibits low strength and a brittle nature. This brittle to ductile transition is observed solely due to the cooling rate at the nanoscale. Elimination of voids as a result of heat treatment is reported as well. Shockley dislocation is observed as the key factor during tensile plastic deformation. Increasing strain rates result in strain hardening and a higher dislocation density in tension. Our computational method is successful in capturing extensive sliding on the {111} shear plane due to dislocation, which leads to necking before fracture. Furthermore, notable mechanical properties are revealed by varying the temperature, size and strain rate. Our results detail a pathway to design machine parts with Inconel-718 alloy efficiently in a bottom-up approach.

Graphical abstract: Deformation mechanisms of Inconel-718 at the nanoscale by molecular dynamics

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Article information


Submitted
23 Dec 2020
Accepted
12 Apr 2021
First published
12 Apr 2021

Phys. Chem. Chem. Phys., 2021,23, 10650-10661
Article type
Paper

Deformation mechanisms of Inconel-718 at the nanoscale by molecular dynamics

A. Faiyad, M. A. M. Munshi, M. M. Islam and S. Saha, Phys. Chem. Chem. Phys., 2021, 23, 10650
DOI: 10.1039/D0CP06614A

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