Nucleation of recrystallized magnesium grains over quasicrystalline phase during severe plastic deformation of a Mg-Zn-Y alloy at room temperature

Singh, Alok; Basha, Dudekula Althaf; Somekawa, Hidetoshi; Tsuchiya, Koichi

doi:10.1016/j.scriptamat.2017.02.039

Cited by 17 publications

(8 citation statements)

References 23 publications

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“…Comparison with data on a wide range of Mg alloys processed by HPT shows that the present processing of the T6-treated Mg-Gd-Y-Zn-Zr alloy results in a grain size that is the smallest ever reported for a Mg alloy [29,[44][45][46][47][48][49][50][51][52]. It is also substantially smaller than grain sizes reported for SPD processed Al-based alloys [19].…”

Section: Microhardness Evolution and Strain Hardening Behavior Duringmentioning

confidence: 50%

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: Microhardness Evolution and Strain Hardening Behavior Duringmentioning

confidence: 50%

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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“…In SPD-processed Al alloys some related phenomena have been observed. For example, Morris et al [45] found that the extent of microstructural refinement and strengthening depended more on solute content than on Mg-Zn-Zr [35,36,43] Mg-Zn [44] Mg [27] Mg-Zn-Y [37] Mg-Al-Zn [38][39][40][41] Mg-Zn-Ca [42] Mg-Gd-Y-Zn-Zr (This work, [15])…”

Section: 92mentioning

confidence: 93%

“…As-cast followed by HPT [15] Solid solution followed by HPT Fig. 10 for comparison [8,11,15,27,[35][36][37][38][39][40][41][42][43][44]. Due to the non-uniform hardness distribution from centre to edge in the reported alloys, the values of hardness plotted in Fig.…”

Section: 92mentioning

confidence: 99%

“…10 are selected at a representative position with average hardness, the position of half radius of disks. Among these alloys, Mg-RE alloys [8,11,37] are subjected to HPT deformation of 5 turns and 10 turns starting from an initial solution-treated condition. During HPT processing the addition of RE elements in Mg alloys causes a more significant refinement than all conventional Mgrich alloys (see Fig.…”

Section: 92mentioning

confidence: 99%

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Microstructure and mechanical properties of a nanostructured Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr supersaturated solid solution prepared by high pressure torsion

et al. 2017

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In this study, a solution-treated Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy was processed by high pressure torsion (HPT) at room temperature, with the aim of producing a material with exceptional mechanical properties. Transmission electron microscopy and X-ray diffraction line broadening analysis reveal that a nanostructured supersaturated solid solution with a mean grain size of ~48 nm and high dislocation density of ~4.7×10 14 m-2 is achieved by HPT deformation. After HPT processing, the present solution-treated samples show finer grains and higher dislocation densities as compared to as-cast samples of this alloy, other solution-treated Mg-RE alloys and conventional Mg alloys deformed using similar HPT processing conditions. This could be attributed to retardation of the dislocation annihilation through enhanced solutedislocation and / or dislocation-dislocation interactions. The higher dislocation density and nanosized grains within supersaturated solid solution cause the microhardness to increase to ~126 HV, which is higher than that of the as-cast Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr (wt.%) alloy processed by HPT, and is also higher than that of any conventional Mg-rich alloy deformed using HPT.

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“…structure by severe plastic deformation (SPD) is an effective way to improve the mechanical properties of Mg-based alloys [5,6]. High pressure torsion (HPT) is capable of producing a more significant grain refinement and higher dislocation density at room temperature compared to other SPD techniques [7,8].…”

Section: Fabrication Of Bulk Ultrafine-grained (Ufg)mentioning

confidence: 99%

Achieving ultra-high hardness of nanostructured Mg-8.2Gd-3.2Y-1.0Zn-0.4Zr alloy produced by a combination of high pressure torsion and ageing treatment

et al. 2018

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A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is subjected to a series of thermal and mechanical treatments involving solution treatment, artificial ageing to peak hardness, high pressure torsion (HPT) and a second artificial ageing. During HPT precipitates dissolve and during the final post-HPT ageing, the supersaturated solid solution decomposes and solutes segregate at grain boundaries. By employing this T6+HPT+T5 treatment, the hardness increases to 156±1 HV, which is much higher than that achieved by any other reported combination of thermal and thermo-mechanical processing of Mg alloys. The ultra-high hardness is due to the combined effects of solute segregation, grain refinement and high dislocation density.

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Nucleation of recrystallized magnesium grains over quasicrystalline phase during severe plastic deformation of a Mg-Zn-Y alloy at room temperature

Cited by 17 publications

References 23 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

Microstructure and mechanical properties of a nanostructured Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr supersaturated solid solution prepared by high pressure torsion

Achieving ultra-high hardness of nanostructured Mg-8.2Gd-3.2Y-1.0Zn-0.4Zr alloy produced by a combination of high pressure torsion and ageing treatment

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