Interfacial segregation induced by severe plastic deformation in a Mg–Zn–Y alloy

Basha, Dudekula Althaf; Sahara, Ryoji; Somekawa, Hidetoshi; Rosalie, Julian M.; Singh, Alok; Tsuchiya, Koichi

doi:10.1016/j.scriptamat.2016.07.021

Cited by 47 publications

(14 citation statements)

References 19 publications

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“…Besides that, the enrichment of Ca atoms at the LAGBs occurs readily in present samples, and the ultrafine-grain instability can be greatly suppressed by solute drag mechanism [59]. The recent works also demonstrate that some particular solutes (such as RE and Zn) can be attracted to the particular defects, such as twin boundaries, grain boundaries and stacking faults in Mg alloys, and the solute segregations are usually considered to be energetically favorable [50,60].…”

Section: Dynamic Activation Of Dislocations and Solute Partitioningmentioning

confidence: 70%

Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength

et al. 2018

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Developing ultra-high strength in rare-earth-free Mg alloys using conventional extrusion process is a great challenge. What is even more difficult is to achieve such a goal at a lower processing cost. In this work, we report a novel low-alloyed Mg-2Sn-2Ca alloy (in wt. %) that exhibits tunable ultra-high tensile yield strength (360e440 MPa) depending on extrusion parameters. More importantly, there is little drop in mechanical properties of this alloy even when it is extruded at a speed several times higher than those used in the reported high strength Mg alloys. Examination of as-extruded microstructures of this Cacontaining Mg alloy reveals that the ultra-high strength is mainly associated with the presence of surprisingly submicron matrix grains (down to~0.32 mm). The results suggest that the Ca addition promotes accumulations of the pyramidal dislocations, which eventually transform into the low angular grain boundaries (LAGBs). The high number density of LAGBs separate the a-Mg matrix via either discontinuous dynamic recrystallization (DDRX) mechanism in the early stage or the continuous dynamic recrystallization (CDRX) mechanism in the later stage of extrusion, which effectively enhances the nucleation rates of the DRXed grains. More importantly, large amount of Ca segregation along LAGBs, accompanied with dynamically precipitated Mg 2 Ca nano-phases, are detected in the present nonseverely deformed samples. It is the combination of solute segregations and numerous Mg 2 Ca nanoprecipitates that contributes to the formation of the ultra-fine grains via pinning mechanism. The ultrafine grains size, Ca enrichment in most LAGBs, and residual Mg 2 Ca nano-precipitates would in turn contribute significantly to the enhancement of the yield strength of the as-extruded Mg-2Sn-2Ca (wt.%) alloy. The low content of alloying elements and the fast one-step extrusion process render the present alloys low-cost and thus have great potential in large-scale industry applications.

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Section: Dynamic Activation Of Dislocations and Solute Partitioningmentioning

confidence: 70%

Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength

et al. 2018

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“…Similar phenomena have been also reported in a HPT processed Mg-Zn-Y alloy by Basha et al . 20 previously.…”

Section: Resultsmentioning

confidence: 95%

Change of Deformation Mechanisms Leading to High Strength and Large Ductility in Mg-Zn-Zr-Ca Alloy with Fully Recrystallized Ultrafine Grained Microstructures

Zheng

Bhattacharjee

Gao

et al. 2019

Sci Rep

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Recently, we have found that fully recrystallized ultrafine-grained (UFG) microstructures could be realized in a commercial precipitation-hardened Magnesium (Mg) alloy. The UFG specimens exhibited high strength and large ductility under tensile test, but underlying mechanisms for good mechanical properties remained unclear. In this study, we have carried out systematic observations of deformation microstructures for revealing the influence of grain size on the change of dominant deformation modes. We found that plastic deformation of conventionally coarse-grained specimen was predominated by {0001} <11–20> slip and {10–12} <10–11> twinning, and the quick decrease of work-hardening rate was mainly due to the early saturation of deformation twins. For the UFG specimens, {10–12} <10–11> twinning was dramatically suppressed, while non-basal slip systems containing < c > component of Burgers vector were activated, which contributed significantly to the enhanced work-hardening rate leading to high strength and large ductility. It was clarified by this study that limited ductility of hexagonal Mg alloys could be overcome by activating unusual slip systems (< c + a > dislocations) in fully recrystallized UFG microstructures.

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“…Many papers have reported the formation of ultrafine grained structures in pure magnesium [3][4][5][6] and AZ31 [7][8][9][10][11] , AZ61 12 , AZ80 13 , AZ91 [14][15][16] , ZK60 [17][18][19] , Mg-Zn-Y 20,21 , Mg-Gd-Y-Zr 22,23 , Mg-Zn-Ca [24][25][26][27] and Mg-Dy-Al-Zn-Zr 28 alloys. The processed alloys exhibit improved strength but also some papers report superplastic behaviour 16,19,22,29,30 , improved hydrogen storage properties 3,[31][32][33][34][35] and improved corrosion resistance 24,27,36 .…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Hardness Evolution in Magnesium Processed by HPT

et al. 2017

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High pressure torsion provides an opportunity to process materials with low formability such as magnesium at room temperature. The present work shows the microstructure evolution in commercially pure magnesium processed using a pressure of 6.0 GPa up to 10 turns of rotation. The microstructure evolution is evaluated using electron microscopy and the hardness is determined using dynamic hardness testing. The results show that the grain refinement mechanism in this material differs from materials with b.c.c. and f.c.c. structures. The mechanism of grain refinement observed at high temperatures also applies at room temperature. The hardness distribution is heterogeneous along the longitudinal section of the discs and is not affected by the amount of deformation imposed to the material.

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Interfacial segregation induced by severe plastic deformation in a Mg–Zn–Y alloy

Cited by 47 publications

References 19 publications

Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength

Development of low-alloyed and rare-earth-free magnesium alloys having ultra-high strength

Change of Deformation Mechanisms Leading to High Strength and Large Ductility in Mg-Zn-Zr-Ca Alloy with Fully Recrystallized Ultrafine Grained Microstructures

Microstructure and Hardness Evolution in Magnesium Processed by HPT

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