Understanding creep in TiAl alloys on the nanosecond scale by molecular dynamics simulations

Molecular dynamics (MD) simulations of creep generally face the problem that the creep most often evolves on time scales hard to capture with MD due to their typically short time step size. Consequently, MD studies of creep often use unrealistically high temperatures and stresses and simplified atomistic models to make creep-like processes happen on computationally accessible time scales. Apparently, this compromises the physical reliability of such studies. To alleviate this problem, we designed an MD model of titanium aluminide (TiAl) with a microstructure matching at least many of the key parameters of experimentally observed microstructures. We applied this MD model with stresses much lower than the ones used in most previous creep studies (well below yield stress) and in the temperature range 0.55TM-0.7TM, with melting temperature TM. Compared to typical previous MD studies, this much more realistic setup produces creep rates more than three orders of magnitude smaller and thus much closer to reality. We identified the driving mechanisms of primary creep on the nanosecond scale that agree very well with recent experimental observations, thus contributing towards the overarching goal of bridging the gap between atomistic creep simulations and continuum-scale creep simulations for engineering applications.

Subjects

Atomistic modeling

Creep

Molecular dynamics

Nanocrystalline

Nanomechanics

Poly-colony

TiAl alloys

DDC Class

530: Physik

540: Chemie

600: Technik

620: Ingenieurwissenschaften

Funding Organisations

Helmholtz-Zentrum Hereon

More Funding Information

The authors gratefully acknowledge the funding of this project within the IDEA framework from Helmholtz-Zentrum Hereon (formerly
Helmholtz-Zentrum Geesthacht), Germany.

Publication version

publishedVersion

Lizenz

https://creativecommons.org/licenses/by/4.0/

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1-s2.0-S0264127521008376-main.pdf

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6.26 MB

Format

Adobe PDF

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Understanding creep in TiAl alloys on the nanosecond scale by molecular dynamics simulations