Energy of Void in FCC Copper Crystal Under Uniaxial Tensile Deformation

LAMMPS

Tammy TancharoensuksavaiMTSE 4040 Final Project

LAMMPS

• Large Scale Atomic/Molecular Massively Parallel Simulator

• uses neighbor lists to keep track of nearby particles which are optimized for systems with particles that are repulsive at short distances

• Open source! ✨"✨

Energy of Void in FCC Copper Crystal Under Uniaxial Tensile Deformation

FCC Cu Crystal - no void

20 x 20 x 20 nm box

Void Sizes & their Nucleation Sites

r=2nm r=3nm r=4nm

Slip Systems

• Schmid’s Law τ = σ *m τ is equal to the stress applied to the material (σ) multiplied by the cosine of the angle with the glide plane (φ) and the cosine of the angle with the glide direction (λ)

• Schmid Factor m = cos(θ)*cos(λ)

Slip Systems

Dislocations

• Dislocation motion in FCC crystals is governed by the critical resolved shear stress via Schmid’s law

• Stacking fault energy has been used to predict energy at a crack tip

• Homogeneous nucleation depends on both Schmid & non-Schmid normal factor

• together they represent resolved shear stress in the direction of slip and resolved tensile stress normal to the slip plane

No Void

• Red BCC • Purple HCP • Grey unknown

No Void

No Void

2nm radius void

• Red BCC • Purple HCP • Grey unknown

2nm radius void

3nm radius void

• Red BCC • Purple HCP • Grey unknown

3nm radius void

4nm radius void

• Red BCC • Purple HCP • Grey unknown

4nm radius void

Conclusion: Energy of FCC Cu Crystal

• Volume remains fixed within system at 377933.0670

• Energy minimizes for every step

• Energy decreases as radius decreases

-114000.0000

-111750.0000

-109500.0000

-107250.0000

-105000.0000

r=5 r=4 r=3 r=2 r=0

Energy by Void Radius Volume remains 377933.0670

References

(1)Das, Ashis, and Gaurav Singh. "Plastic Deformation and Failure Studies near a Void for Copper-

aluminium Alloy via Molecular Dynamics Simulation." Thesis. Department of Metallurgical and

Materials Engineering National Institute of Technology, Rourkela, 2014. Print.

(2)Tschopp, M., Spearot, D., & Mcdowell, D. (2007). Atomistic simulations of homogeneous dislocation

nucleation in single crystal copper. Modelling and Simulation in Materials Science and Engineering,

693-709.

(3)Wang, T., Wang, Y., Hsieh, T., Chang, S., & Cheng, Y. (n.d.). Copper voids improvement for the

copper dual damascene interconnection process. Journal of Physics and Chemistry of Solids,

566-571.

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