Hardening by slip-twin and twin-twin interactions in FeMnNiCoCr

M. Bönisch, Y. Wu, H. Sehitoglu

Research output: Contribution to journalArticlepeer-review

Abstract

To enhance strain hardening of alloys beyond levels accessible by forest hardening slip-twin interactions and twin-twin interactions have been proposed. The high entropy alloy FeMnNiCoCr constitutes a prominent example of exceptionally pronounced strain hardening instigated by profuse slip-twin/twin-slip and twin-twin interaction at cryogenic temperatures. In the current study, we perform uniaxial straining experiments on single crystals at 77 K. The <144>Tension crystal shows the potential ease of twin progression for slip-twin interaction (softening) in contrast to the difficulty for twin advancement in <122>Tension, <111>Tension and <001>Compression cases (hardening). The corresponding self and latent hardening coefficients derived from the data reveal that slip-twin latent moduli are much smaller than twin-twin latent moduli. Unlike previous undertakings, this study demonstrates a novel approach to assess latent hardening where plastic straining is implemented in a monotonic fashion and primary and latent systems operate simultaneously. To predict the flow stress depending on crystal orientation and as a function of strain a numerical model is proposed using the obtained hardening moduli. It emerges that the magnitude of residual Burgers vectors originating from twin-related reactions can explain the experimental hardening/softening trends. These results hold considerable promise for a quantitative description of strain hardening in metals and alloys.

Original languageEnglish (US)
Pages (from-to)391-403
Number of pages13
JournalActa Materialia
Volume153
DOIs
StatePublished - Jul 2018

Keywords

  • High entropy alloys
  • Latent hardening
  • Residual burgers vector
  • Slip-twin interaction
  • Strain softening
  • Twin-twin interaction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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