Hierarchical precipitates, sequential deformation-induced phase transformation, and enhanced back stress strengthening of the micro-alloyed high entropy alloy
IF 8.3 1区 材料科学Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY
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引用次数: 0
Abstract
We report the annealing time-dependent microstructures and deformation mechanisms of the novel face-centered cubic Fe49.5Mn30Co10Cr10C0.2Ti0.1V0.1Mo0.1 HEA. Three types of precipitates, σ-phase, Cr-rich MC-type carbides, and nano-scale (Ti, V, Mo)C, are present after cold-rolling and annealing at 600 °C. Such hierarchical precipitates could lead to sluggish recrystallization and grain growth upon annealing. The partially recrystallized microstructures and hierarchical precipitates could lead to a high yield strength even for prolonged annealing conditions. Deformation mechanisms change with annealing time. The materials annealed for short times (< 2 h) are deformed by dislocation glide, deformation twinning, and deformation-induced ε phase. A longer annealing time (> 10 h) triggers a multi-variant ε phase, reverse transformation from ε to γ, and the multi-step sequential transformation, γ → ε → reverse transformed γ from ε → ε transformed from the reverse transformed γ. Further, materials annealed for longer times shows a higher contribution of back stress strengthening, which could be attributed to the increase in γ/ε and γ/σ interfaces. The activation of various deformation mechanisms and high back stress strengthening could lead to a superior strain hardening capacity and strength-ductility combination (YS: 699 MPa, UTS: 1041 MPa, TE: 45%) of the material annealed for 10 h. The present work provides the novel microstructure design solution of the metastable high entropy alloys with exceptional mechanical properties, utilizing hierarchical precipitates, sequential deformation-induced phase transformation, and enhanced back stress strengthening.
期刊介绍:
Acta Materialia serves as a platform for publishing full-length, original papers and commissioned overviews that contribute to a profound understanding of the correlation between the processing, structure, and properties of inorganic materials. The journal seeks papers with high impact potential or those that significantly propel the field forward. The scope includes the atomic and molecular arrangements, chemical and electronic structures, and microstructure of materials, focusing on their mechanical or functional behavior across all length scales, including nanostructures.