Contribution of extension twinning to plastic strain at low stress stage deformation of a Mg-3Al-1Zn alloy

Chen, P.; Li, B.; Culbertson, Duke; Jiang, Yanyao

doi:10.1016/j.msea.2017.10.038

Cited by 73 publications

(7 citation statements)

References 43 publications

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“…It is now well understood that the brittleness of Mg arises from its largely anisotropic critical resolved shear stress between basal slip and non-basal slip, and thus restricted number of easily activated slip systems. Accordingly, extensive efforts have been devoted to exploring the activation of deformation twinning in Mg [1,[3][4][5][6][7][8][9][10][11][12], which is an important category of deformation mode to meet the von Mises' criterion that there must be at least five independent deformation modes for a crystal to undergo an arbitrarily imposed deformation. However, the nucleation mechanism of the {1012} twin [9,10,[13][14][15][16][17][18][19][20][21][22], which is the predominant twinning mode in Mg, still remains elusive.…”

Section: Introductionmentioning

confidence: 99%

Nucleation of {1012} Twins in Magnesium through Reversible Martensitic Phase Transformation

Ombogo

Zahiri

et al. 2020

Metals

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We report the discovery of a rigorous nucleation mechanism for {101¯2} twins in hexagonal close-packed (hcp) magnesium through reversible hcp-tetragonal-hcp martensitic phase transformations with a metastable tetragonal phase as the intermediate state. Specifically, the parent hcp phase first transforms to a metastable tetragonal phase, which subsequently transforms to a twinned hcp phase. The evanescent nature of the tetragonal phase severely hinders its direct observation, while our carefully designed molecular dynamics simulations rigorously reveal the critical role of this metastable phase in the nucleation of {101¯2} twins in magnesium. Moreover, we prove that the reversible hcp-tetragonal-hcp phase transformations involved in the twinning process follow strict orientation relations between the parent hcp, intermediate tetragonal, and twin hcp phases. This phase transformation-mediated twinning mechanism is naturally compatible with the ultrafast twin growth speed. This work will be important for a better understanding of the twinning mechanism and thus the development of novel strategies for enhancing the ductility of magnesium alloys.

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Section: Introductionmentioning

confidence: 99%

Nucleation of {1012} Twins in Magnesium through Reversible Martensitic Phase Transformation

Ombogo

Zahiri

et al. 2020

Metals

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“…The CRSS of

twins in Mg, Zr, and Ti are 30 MPa, 165 MPa, and 260 MPa, respectively [ 49 , 53 , 54 ], which are less than the values of other twins. Therefore, the

twins are more active in hcp metals, especially in Mg.

twinning has been popularly observed by experiments and atomistic simulations, and the mechanism of

twinning has been widely discussed [ 7 , 8 , 10 , 11 , 16 ]. Figure 3 shows the initial plasticity of Zr single crystal under c -axis tension.…”

Section: Resultsmentioning

confidence: 99%

“…Factors influencing the twinning modes include the c / a ratios, lattice packing densities, interplanar spacings, stacking fault energies, and so on. In Mg and its alloys,

tension twin and

compression twin are the most popular twinning modes [ 7 , 8 , 9 , 10 ]. In Ti and its alloys, the most commonly observed tension twins are

and

, and the compression twins are

and

[ 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

The Plastic Deformation Mechanisms of hcp Single Crystals with Different Orientations: Molecular Dynamics Simulations

Tang

Mao

et al. 2021

Materials

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The deformation mechanisms of Mg, Zr, and Ti single crystals with different orientations are systematically studied by using molecular dynamics simulations. The affecting factors for the plasticity of hexagonal close-packed (hcp) metals are investigated. The results show that the basal <a> dislocation, prismatic <a> dislocation, and pyramidal <c + a> dislocation are activated in Mg, Zr, and Ti single crystals. The prior slip system is determined by the combined effect of the Schmid factor and the critical resolved shear stresses (CRSS). Twinning plays a crucial role during plastic deformation since basal and prismatic slips are limited. The 101¯2 twinning is popularly observed in Mg, Zr, and Ti due to its low CRSS. The 101¯1 twin appears in Mg and Ti, but not in Zr because of the high CRSS. The stress-induced hcp-fcc phase transformation occurs in Ti, which is achieved by successive glide of Shockley partial dislocations on basal planes. More types of plastic deformation mechanisms (including the cross-slip, double twins, and hcp-fcc phase transformation) are activated in Ti than in Mg and Zr. Multiple deformation mechanisms coordinate with each other, resulting in the higher strength and good ductility of Ti. The simulation results agree well with the related experimental observation.

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“…On the other hand, in the TMAZ (P1, P3, P4, P6, P7 and P9), both small DRX grains and abundant twins were found, and the morphology of these twins were consistent with the twins [23,24]. The original grains were refined due to the twinning and DRX.…”

Section: Microstructure Evolution During Fspmentioning

confidence: 98%

“…With the extension of the twinning, the grains were divided into many sub-grains and the crystal orientations were rotated from soft orientation to hard orientation. Then, the refinement strengthening and texture strengthening gave rise to the increase of SHR [23].…”

Section: The Deformation Mechanism During Tensile Testmentioning

confidence: 99%

The effect of the inhomogeneous microstructure and texture on the mechanical properties of AZ31 Mg alloys processed by friction stir processing

Peng

Zhang

Huang

et al. 2019

Journal of Alloys and Compounds

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Contribution of extension twinning to plastic strain at low stress stage deformation of a Mg-3Al-1Zn alloy

Cited by 73 publications

References 43 publications

Nucleation of {1012} Twins in Magnesium through Reversible Martensitic Phase Transformation

Nucleation of {1012} Twins in Magnesium through Reversible Martensitic Phase Transformation

The Plastic Deformation Mechanisms of hcp Single Crystals with Different Orientations: Molecular Dynamics Simulations

The effect of the inhomogeneous microstructure and texture on the mechanical properties of AZ31 Mg alloys processed by friction stir processing

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