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In this paper, the evolution of microstructure and mechanical properties in the Fe-28Ni-20Co-11.5Al-2.5Ta-0.05B (at.%) alloy were systematically studied. The findings elucidate that the absence of thermoelastic martensitic transformation following cyclic loading signifies the lack of superelasticity in solid solution state. Subsequent to the 72 h aging process at 600°C, the emergence of small (4 ± 2 nm) Ni3Al precipitates with an L12 structure was observed within the grains. The degree of misfit between the precipitate and matrix was found to be only 0.28%. The precipitates contribute to the strength through ordering strengthening, ultimately increasing the strength of austenite. In the method this study introduces, there is neither a need for significant cold rolling deformation and prolonged annealing to form specific recrystallization texture nor preparation of large grain sized specimens equivalent to single crystals. The coherent relationship between the Ni3Al phase and matrix induces the occurrence of thermoelastic martensitic transformation, which results in a 1.3% superelasticity. [ABSTRACT FROM AUTHOR]

The effects of cold deformation on the microstructure, texture evolution and mechanical properties of TB8 alloy during cold rolling (CR) were investigated. The results show that grain size decreases with the increase in thickness reduction. Meanwhile, the textures change from initial {110}<001> and {113}<332> to α-fiber components ({112}<110>, {113}<110>) and {001}<110> orientation after cold rolling to a thickness reduction of 50%. Increasing the thickness reduction to 67%, α-fiber textures are enhanced along with the appearance of γ-fiber textures. Increasing the thickness reduction further to 83%, γ-fiber textures become dominated. Both grain refinement and texture components contribute to the enhancement of strength after cold rolling. The effect of textures on the mechanical properties are discussed briefly. [ABSTRACT FROM AUTHOR]

While a high density of nano twins can effectively enhance alloys, it also leads to a significant reduction in ductility, similar to other nanostructures. In this work, a deformation strategy combining cold rolling and warm rolling has been employed on a nanotwinned Fe-25Mn-0.5C steel to improve ductility. A high density of nano twins was introduced in the coarse-grained matrix first by cold rolling for high strength. Subsequent warm rolling at 500 °C sheared the large nano twin bundles, resulting in a mixed microstructure consisting of nano twins and more randomly oriented refined grains. Planar slipping of dislocations, instead of twinning, dominates the tensile processes, which brings strong pile-up and continuous work-hardening. Compared with the cold-rolled counterpart with full nano twins, the one with a mixed microstructure exhibits three times higher tensile elongation (21.3 % vs. 5.6 %) while maintaining similar tensile strengths (about 1440 MPa). The evolution of microstructures and the underlying strengthening mechanisms of the mixed microstructure were extensively discussed. Additionally, a cold-rolled and statically annealed sample was also included for comparison. [ABSTRACT FROM AUTHOR]

Most refractory high-entropy alloys (RHEAs) with Al possess excellent strength but low elongation. Low ductility is generally induced by the formation of brittle phases after long-term heat treatment. Here, we demonstrate a new strategy to optimize strength-ductility in RHEAs through cold rolling-annealing treatments. The Zr 35 Ti 30 Nb 20 Al 10 Ta 5 RHEA was cold rolled followed by annealing. A high tensile yield strength of ∼997 MPa with an elongation of ∼20% was obtained. Several factors together optimize the mechanical properties. First, the high-density dislocation entanglements introduced by cold rolling and short-time annealing are beneficial to uniform strain hardening and ductility. Second, short-term annealing can prevent the generation of the brittle LAVES phase in Al-containing RHEAs. Third, the B2 nanoprecipitates are dispersed in the BCC matrix phase, strengthening the alloys. Fourth, the fine grain size induced by cold rolling and short annealing times contributes to the strength. • Zr 35 Ti 30 Nb 20 Al 10 Ta 5 RHEA with excellent strength and ductility was prepared via cold rolling-annealing technology. • A high tensile yield strength of 997 MPa with an elongation of 20% was obtained. • Cold rolling-annealing can avoid the formation of brittle LAVES phase. • Adjustment of dislocation morphology and grain size by cold rolling-annealing can optimize mechanical properties. [ABSTRACT FROM AUTHOR]