Dynamic martensitic phase transformation in single-crystal silver microcubes

Ramathasan Thevamaran, Claire Griesbach, Sadegh Yazdi, Mauricio Ponga, Hossein Alimadadi, Olawale Lawal, Seog Jin Jeon, Edwin L. Thomas*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The ability to transform the crystal structure of metals in the solid state enables tailoring their physical, mechanical, electrical, thermal, and optical properties in unprecedented ways. We demonstrate a martensitic phase transformation from a face-centered-cubic (fcc) structure to a hexagonal-close-packed (hcp) structure that occurs in nanosecond timescale in initially near-defect-free single-crystal silver (Ag) microcubes impacted at supersonic velocities. Impact-induced high pressure and high strain rates in Ag microcubes cause impact orientation dependent extreme micro- and nano-structural transformations. When a microcube is impacted along the [100] crystal symmetry direction, the initial fcc structure transforms into an hcp crystal structure, while impact along the [110] direction does not produce phase transformations, suggesting the predominant role played by the stacking faults generated in the [100] impact. Molecular dynamics simulations at comparable high strain rates reveal the emergence of such stacking faults that coalesce, forming large hcp domains. The formation of hcp phase through the martensitic transformation of fcc Ag shows new potential to dramatically improve material properties of low-stacking-fault energy materials.
Original languageEnglish
JournalActa Materialia
Volume182
Pages (from-to)131-143
ISSN1359-6454
DOIs
Publication statusPublished - 2020

Keywords

  • Phase transformation
  • Gradient nano grained metals
  • Silver
  • Fcc
  • Hcp

Cite this

Thevamaran, R., Griesbach, C., Yazdi, S., Ponga, M., Alimadadi, H., Lawal, O., Jeon, S. J., & Thomas, E. L. (2020). Dynamic martensitic phase transformation in single-crystal silver microcubes. Acta Materialia, 182, 131-143. https://doi.org/10.1016/j.actamat.2019.10.006