Hardening by slip-twin and twin-twin interactions in FeMnNiCoCr. (July 2018)

• Record Type: Journal Article
• Authors: Bönisch, M.; Wu, Y.; Sehitoglu, H.
• Is Part Of: Acta materialia. Volume 153(2018)
• Page Start: 391
• Page End: 403
• Publication Date: 2018-07
• Subjects: High entropy alloys -- Residual burgers vector -- Strain softening -- Slip-twin interaction -- Twin-twin interaction -- Latent hardening; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2018.04.054
• Languages: English
• ISSNs: 1359-6454

Abstract

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. Graphical abstract: Image 1