Elastic energy and interactions between twin boundaries in nanotwinned gold

• Published in: Computational materials science 2023-09, Vol.228, p.112355, Article 112355
• Main Authors: Woguem, Yen Fred, Godard, Pierre, Durinck, Julien, Brochard, Sandrine
• Format: Article
• Language: English
• Subjects: Condensed Matter; Elastic energy; Excess volume; Gold; Materials Science; Molecular statics; Physics; Twin boundary
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2023.112355

Nanotwinned metals exhibit a surprising combination of ultrahigh strength and high ductility. We have performed atomistic simulations in gold to study interactions between coherent twin boundaries (CTBs) and between incoherent twin boundaries (ITBs) for two extreme cases: with close surfaces and without any surface, in order to simulate a relaxed or a constrained system. The estimated displacement fields give the extension of interactions between twin boundaries which are 6 atomic planes for the CTB and in the range of 30–42 atomic planes for the Σ3{112} ITB in the relaxed system. The displacement field in the constrained system is, to a very good approximation, the difference of the displacement field in the relaxed system and a homogeneous quantity which depends on the excess volumes. The elastic strain introduced by the twin boundaries in the constrained system and the associated elastic energy γexcess are deduced from the excess volumes. Our study highlights how the mechanical behaviour (e.g. the yield strength) of samples with TBs separated by distances less than a critical distance whose order of magnitude is (103−105)δTB≈(0.5−360)nm can be affected. [Display omitted] •Twin boundaries (TBs) generate elastic displacement fields and hence excess volumes.•Atomistic simulations on coherent and {112} incoherent TBs have been performed.•The interaction extensions are deduced from these displacement fields in gold.•In constrained systems, an additional elastic field comes from the excess volumes.•The associated elastic energy has been computed and compared to simulations.