Phase evolution in two-phase alloys during severe plastic deformation

Pant, Nirab; Verma, Nisha; Ashkenazy, Yinon; Bellon, Pascal; Averback, Robert S

doi:10.1016/j.actamat.2021.116826

Cited by 10 publications

(3 citation statements)

References 40 publications

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“…In ref. [78], the competition between the dissolution and formation of precipitates during SPD was investigated using molecular dynamics simulations. The case for interacting alloy components has been studied.…”

Section: Grain Size Microhardness Lattice Periodmentioning

confidence: 99%

Structure Refinement and Fragmentation of Precipitates under Severe Plastic Deformation: A Review

et al. 2022

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During severe plastic deformation (SPD), the processes of lattice defect formation as well as their relaxation (annihilation) compete with each other. As a result, a dynamic equilibrium is established, and a steady state is reached after a certain strain value. Simultaneously, other kinetic processes act in opposite directions and also compete with each other during SPD, such as grain refinement/growth, mechanical strengthening/softening, formation/decomposition of solid solution, etc. These competing processes also lead to dynamic equilibrium and result in a steady state (saturation), albeit after different strains. Among these steady-state phenomena, particle fragmentation during the second phase of SPD has received little attention. Available data indicate that precipitate fragmentation slows down with increasing strain, though saturation is achieved at higher strains than in the case of hardness or grain size. Moreover, one can consider the SPD-driven nanocrystallization in the amorphous phase as a process that is opposite to the fragmentation of precipitates. The size of these crystalline nanoprecipitates also saturates after a certain strain. The fragmentation of precipitates during SPD is the topic of this review.

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Section: Grain Size Microhardness Lattice Periodmentioning

confidence: 99%

Structure Refinement and Fragmentation of Precipitates under Severe Plastic Deformation: A Review

et al. 2022

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“… 6 , 7 Additionally, they propose the effective temperature model to explain the observation of high solute superstation tendencies under the high-strain regime. 7 , 8 However, another factor that can influence the experimental observations in these processes is the interaction of the deforming material with the ambient environment, which consists of reactive gases such as oxygen. In the past, metastable supersaturated phases and amorphous structures have been reported to form in several alloys (Nb–B, Cu–Ta, Cu–Nb, and Cu–Ag) on extended deformation by mechanical alloying.…”

Section: Introductionmentioning

confidence: 99%

“…These challenges limit the knowledge of the microstructural transformation pathways during such extended shear deformation processing. Detailed work by P. Bellon and group highlights the strain-dependent modes of microstructural evolution categorized by low strain (<100), where interfacial instabilities dominate, while at high strain (>100) where the atomic mixing can be seen. , Additionally, they propose the effective temperature model to explain the observation of high solute superstation tendencies under the high-strain regime. , However, another factor that can influence the experimental observations in these processes is the interaction of the deforming material with the ambient environment, which consists of reactive gases such as oxygen. In the past, metastable supersaturated phases and amorphous structures have been reported to form in several alloys (Nb–B, Cu–Ta, Cu–Nb, and Cu–Ag) on extended deformation by mechanical alloying. − In two examples, the grain boundary excess of oxygen in nanocrystalline (NC) Al was shown to inhibit the grain boundary migration, while the Zenner pinning effect of oxide nanoparticles was shown to stabilize the NC structure in the Fe–Mg ball-milled alloy .…”

Section: Introductionmentioning

confidence: 99%

Extended Shear Deformation of the Immiscible Cu–Nb Alloy Resulting in Nanostructuring and Oxygen Ingress with Enhancement in Mechanical Properties

Gwalani

Pang

et al. 2022

ACS Omega

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Deformation processing of immiscible systems is observed to disrupt thermodynamic equilibrium, often resulting in nonequilibrium microstructures. The microstructural changes including nanostructuring, hierarchical distribution of phases, localized solute supersaturation, and oxygen ingress result from high-strain extended deformation, causing a significant change in mechanical properties. Because of the dynamic evolution of the material under large strain shear load, a detailed understanding of the transformation pathway has not been established. Additionally, the influence of these microstructural changes on mechanical properties is also not well characterized. Here, an immiscible Cu-4 at. % Nb alloy is subjected to a high-strain shear deformation (∼200); the deformation-induced changes in the morphology, crystal structure, and composition of Cu and Nb phases as a function of total strain are characterized using transmission electron microscopy and atom probe tomography. Furthermore, a multimodal experiment-guided computational approach is used to depict the initiation of deformation by an increase in misorientation boundaries by crystal plasticity-based grain misorientation modeling (strain ∼0.6). Then, co-deformation and nanolamination of Cu and Nb are envisaged by a finite element method-based computational fluid dynamic model with strain ranging from 10 to 200. Finally, the experimentally observed amorphization of the severely sheared supersaturated Cu–Nb–O phase was validated using the first principle-based simulation using density functional theory while highlighting the influence of oxygen ingress during deformation. Furthermore, the nanocrystalline microstructure shows a >2-fold increase in hardness and compressive yield strength of the alloy, elucidating the potential of deformation processing to obtain high-strength low-alloyed metals. Our approach presents a step-by-step evolution of a microstructure in an immiscible alloy undergoing severe shear deformation, which is broadly applicable to materials processing based on friction stir, extrusion, rolling, and surface shear deformation under wear and can be directly applied to understanding material behavior during these processes.

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Titanium content and columnar particles effect on the deformation behaviors of nanocrystalline Ni–Ti alloy with GBAZ segregation

et al. 2023

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Phase evolution in two-phase alloys during severe plastic deformation

Cited by 10 publications

References 40 publications

Structure Refinement and Fragmentation of Precipitates under Severe Plastic Deformation: A Review

Structure Refinement and Fragmentation of Precipitates under Severe Plastic Deformation: A Review

Extended Shear Deformation of the Immiscible Cu–Nb Alloy Resulting in Nanostructuring and Oxygen Ingress with Enhancement in Mechanical Properties

Titanium content and columnar particles effect on the deformation behaviors of nanocrystalline Ni–Ti alloy with GBAZ segregation

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