The evolution of microstructure and micro-texture in a metastable Fe45Co35Cr10V10 medium-entropy alloy subjected to cold rolling

Abstract

Microstructure and micro-texture evolution in a Fe45Co35Cr10V10 medium-entropy alloy under 10‐–88% cold rolling was investigated by electron backscattering diffraction. The variant graph method reconstructed parent γ grain orientations at 20, 30 and 40% thickness reduction to determine the operative orientation relationships (ORs) with the child ε and α′-martensite phases and to study variant selection. The parent γ phase accommodates deformation by faulting, slip, shear banding and martensitic phase transformation via the γ→ε→α′and γ→α′pathways. The ε and α′ -martensite variant selection occurs within individual parent γ grains but not in the bulk microstructure. Variant pairing in α′-martensite shifts from a preference for the same crystallographic packet group to the same Bain group with increasing thickness reduction.The development of the Brass-type micro-texture in the parent γ phase beyond 40% thickness reduction is attributed to Cuγ and Sγ orientations transforming to ε and α′-martensite, along with shear banding. The micro-texture of ε-martensite records maximum intensities for ∼011¯537¯42ε and ∼112¯61¯1¯21ε on the hkil-fibre and originating from ∼Cuγ and Sγ via the Shoji-Nishiyama OR. The α′-martensite micro-texture is characterised by the αα′, γα′ and βα′ fibres. The βα′ -fibre forms between 20% and 60% thickness reduction and rotates towards stable orientations along the αα′-fibre at higher thickness reductions. Modelling shows that orientations along the βα′ and γα′ - fibres stem from ∼Brγ and ∼Sγ and those along the αα′-fibre originate from Gγ, Brγ, Cuγ, and Sγ.