Slip mode dependency of dislocation shearing and looping of precipitates in Mg alloy WE43

Bhattacharyya, Jishnu J.; Wang, Fulin; Stanford, Nicole; Agnew, Sean R.

doi:10.1016/j.actamat.2017.12.043

Cited by 118 publications

(27 citation statements)

References 35 publications

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“…indicates that the twins are { 101 ̅ 1 }< 112 ̅ 0 > compression twins [28]. [33]. From the present TEM observations, it can be deduced that during HPT processing the nanosized β′ precipitates are sheared by many dislocations and eventually decompose.…”

Section: Microstructure Evolution After Hpt Processingmentioning

confidence: 62%

Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates

Sun

Qiao

Zheng

et al. 2018

Materials Science and Engineering: A

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The influence of the nanosized rare earth (RE) containing precipitates on grain refinement during severe plastic deformation is investigated in detail through a study of high pressure torsion (HPT) processing of a solution treated and aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%). In the early stages of HPT deformation, dislocation generation and pileup is promoted by the nanosized RE containing β′ precipitates. With increasing strain, the precipitates are cut by the moving dislocations and gradually dissolve into the α-Mg matrix aided by dislocations serving as diffusion channels for solute atoms. After HPT for 2 turns, the hardness reaches a maximum and on further deformation the microhardness decreases although the microstructure refinement continues and the dislocation density is increasing. This is due to the continuing dissolution of precipitates, which dominates the hardness evolution at this stage. After HPT for 16 turns, the precipitates have almost completely dissolved and the average grain size is ~33 nm, which is the smallest ever reported for a Mg-or Al-based alloy. The present peak-aged Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy exhibits quite different microstructure evolution and hardening behaviour during HPT processing as compared to both the cast and the solutionized Mg-Gd-Y-Zn-Zr alloy.

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Section: Microstructure Evolution After Hpt Processingmentioning

confidence: 62%

Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates

Sun

Qiao

Zheng

et al. 2018

Materials Science and Engineering: A

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“…Precipitate shearing by dislocations is normally found in the case of coherent precipitates ; the matrix dislocation enters the precipitate through the coherent interface and slips along the most suitable slip plane. This phenomenon is most clear when the matrix and the precipitate share the same crystallographic lattice (for instance, γ precipitates in a γ matrix in Ni-based superalloys [57] or Guinier-Preston zones in Al-Cu alloys [29]) but it has also been reported in the case of basal dislocations with β precipitates in Mg-RE alloys [58,59]. Under these circumstances, the CRSS necessary to shear the precipitate depends on the coherency strain, the modulus mismatch, the chemical strengthening and, in the case of ordered precipitates, on the energy penalty due to the formation of antiphase boundaries [60].…”

Section: Dislocation/precipitate Interaction Mechanisms At Finite Temmentioning

confidence: 96%

“…The presence of dislocation pile-ups before precipitate shearing has also been experimentally reported in Mg-Al [20] and Mg-Nd [64], supporting our atomistic results. It should be also noted that precipitate shearing in Mg alloys by either prismatic or pyramidal dislocations was not observed because of the lack of crystallographic continuity between the corresponding slip planes in the matrix and in the precipitate [59]. Thus, the strength of Mg alloys is limited by the low CRSS for basal slip, which is always the main plastic deformation mechanism.…”

Section: Dislocation/precipitate Interaction Mechanisms At Finite Temmentioning

confidence: 99%

Basal dislocation/precipitate interactions in Mg–Al alloys: an atomistic investigation

Esteban-Manzanares

Papadimitriou

et al. 2019

Modelling Simul. Mater. Sci. Eng.

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The interaction between edge basal dislocations and β-Mg 17 Al 12 precipitates was studied using atomistic simulations. A strategy was developed to insert a lozenge-shaped Mg 17 Al 12 precipitate with Burgers orientation relationship within the Mg matrix in an atomistic model ensuring that the matrix/precipitate interfaces were close to minimum energy configurations. It was found that the dislocation bypassed the precipitate by the formation of an Orowan loop, that entered the precipitate. Within the precipitate, the dislocation was not able to progress further until more dislocations overcome the precipitate and push the initial loop to shear the precipitate along the (110) plane, parallel to the basal plane of Mg. This process was eventually repeated as more dislocations overcome the precipitate and this mechanism of dislocation/precipitate interaction was in agreement with experimental observations. Moreover, the initial resolved shear stress to bypass the precipitate was in agreement with the predictions of the Bacon-Kocks-Scattergood model.

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“…9c) by basal dislocations. Nevertheless, precipitate shearing in Mg alloys by either prismatic or pyramidal dislocations has not been observed because of the lack of crystallographic continuity between the corresponding slip planes in the matrix and in the precipitate [45].…”

Section: Interaction Mechanisms Of Basal Dislocations With # Precipitmentioning

confidence: 99%

Interactions between basal dislocations and β1′ precipitates in Mg–4Zn alloy: Mechanisms and strengthening

Alizadeh

LLorca

2020

Acta Materialia

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Slip mode dependency of dislocation shearing and looping of precipitates in Mg alloy WE43

Cited by 118 publications

References 35 publications

Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates

Exceptional grain refinement in a Mg alloy during high pressure torsion due to rare earth containing nanosized precipitates

Basal dislocation/precipitate interactions in Mg–Al alloys: an atomistic investigation

Interactions between basal dislocations and β1′ precipitates in Mg–4Zn alloy: Mechanisms and strengthening

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