Ultrafine-grained Mg–9Li–1Zn alloy sheets exhibiting low temperature superplasticity

Kim, W.J.; Kim, M.J.; Wang, J.Y.

doi:10.1016/j.msea.2009.03.089

Cited by 67 publications

(21 citation statements)

References 15 publications

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“…• C like ECAP was performed, showed a high elongation near 70% which was lower than that observed for other superplastic two phase MgLi alloys [6,7,10]. However, the sample after HPT carried out at lower temperature showed significantly better superplastic properties after ECAP than the other alloys [10].…”

Section: Resultsmentioning

confidence: 75%

“…The strain rate sensitivities under the optimum superplastic conditions were measured as m ≈ 0.4-0.6. The superplastic forming was also reported in ultrafinegrained Mg-9Li-1Zn (LZ91) alloy sheets prepared through high-speedratio differential speed rolling (HRDSR) [7] giving in consequence the grains of α and β phases reduced to the size of ≈ 1 µm. The HRDSRed alloy exhibited the enhanced strength and ductility at room temperature and excellent low temperature superplasticity in the temperature range 423-523 K. The Mg-Li alloy with 8 wt% Li was processed by high-pressure torsion (HPT) to achieve ultrafine grains with the average grain size of 500 nm.…”

Section: Introductionmentioning

confidence: 59%

“…One can see that in alloy 1 hardness decreases from 70 HV to 60 HV after the first pass, then slightly raises to 62 HV and then decreases again, while in alloy 2 it decreases gradually from 61 to 60 after the first pass, then to 58 HV after the second one and then stabilizes. In another work on twophase MgLiZn alloys, a slight increase of hardness was observed after HRDSR [7], however it might have been due to different deformation treatment leading to lower hardness (50 HV). In the single phase hexagonal MgLi alloys hardening was reported to result from precipitates and work.…”

Section: Resultsmentioning

confidence: 93%

“…In both alloys some nonhomogeneity of deformation can be seen, however it is larger in alloy 2. It seems that it is caused by lower strength of the bcc Li rich phase, which more easily undergoes deformation [6][7][8][9][10]. TEM microstructure of alloy 1 after the first pass is shown at a relatively low magnification; softening is connected with cross slip and the dislocation climb process [10] which may be a reason for small deformation hardening (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Modification of Microstructure and Properties of Extruded Mg-Li-Al Alloys of α and α+ β Phase Composition using ECAP Processing

et al. 2017

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Two magnesium based alloys containing 4.5 wt% Li and 1.5 wt% Al (alloy 1) and 9 wt% Li and 1.5 wt% Al (alloy 2) were cast under argon atmosphere and hot extruded at 350• C. Microstructure of alloy 1 consisted of hexagonal α phase of average grain size 20 µm and small aluminum rich precipitates being the most probably AlLi2Mg phase. Alloy 2 in the extruded form consisted of lamellas of α + β phases of thickness 5-20 µm and length above 100 µm. Significant grain refinement down to about 2 µm was observed in one-phase hexagonal (hcp) alloy 1 after one pass of ECAP processing with helical component. Two-phase (hcp + bcc) alloy 2 showed higher non-homogeneity after the first equal channel angular pressing pass due to easier deformation of softer bcc phase, while both, α and β phases exhibited low angle grain boundaries. The hardness and the yield strength of the alloys were higher for alloy 1 (68 HV and 205 MPa, respectively) than those of alloy 2 (61 HV and 175 MPa). Subsequent equal channel angular pressing passes were performed at lower extrusion stress. The hardness of both alloys did not change significantly after subsequent equal channel angular pressing passes and revealed tendency to decrease. Two-phase alloy showed superplastic properties already after one equal channel angular pressing pass at 160• C with grain growth after superplastic tensile testing. Single phase hcp alloy did not show such properties after 1 pass, but after a few equal channel angular pressing passes it could be superplastically formed.

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Section: Resultsmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

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Modification of Microstructure and Properties of Extruded Mg-Li-Al Alloys of α and α+ β Phase Composition using ECAP Processing

et al. 2017

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“…Mg-Li based alloys and composites, known as the lightest metallic structural materials, have great potential for use not only in aerospace and military but also in automobiles and electrical appliances, due to their attractive features of high values of specific strength, specific modulus, and electromagnetic shielding properties [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Preparation and surface modification of submicron YAl2 particles by mixed milling with magnesium for fabricating YAl2p/MgLiAl composites

Zhang¹,

Wu²,

Sha³

et al. 2014

Powder Technology

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Superplasticity at Elevated Temperature of a Coarse‐Grained Mg–Li Alloy

et al. 2013

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Tensile tests on Mg-10.73Li-4.49Al-0.52Y alloy processed by equal channel angular pressing (ECAP) are conducted at 473-623 K with initial strain rates of 5 Â 10 À4 -1 Â 10 À2 s À1 and the microstructures and the deformation mechanism are investigated. Homogeneous microstructure with an average coarse grain size of 154.6 mm is obtained after ECAP process. The results indicate that the alloy exhibits significant superplasticity with a maximum elongation of 512% at 523 K with initial strain rate of 5 Â 10 À4 s À1 . Even with strain rate of 1 Â 10 À2 s À1 , the elongations exceed 150% at all temperatures, which suggests that the alloy exhibits notable high strain rate quasi-superplasticity. Under the optimum superplastic condition, the value of the strain rate sensitivity is 0.53 and the activation energy is 89.7 kJ mol À1 , indicating that the dominant deformation mechanism in this alloy is grain boundary sliding (GBS) controlled by a combination of grain boundary diffusion and lattice diffusion. Grain refinement occurs during pre-heating and deformation, which is favor for GBS. The nucleation, growth, and coalescence of cavities are the main failure mechanism during superplastic deformation.

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Ultrafine-grained Mg–9Li–1Zn alloy sheets exhibiting low temperature superplasticity

Cited by 67 publications

References 15 publications

Modification of Microstructure and Properties of Extruded Mg-Li-Al Alloys of α and α+ β Phase Composition using ECAP Processing

Modification of Microstructure and Properties of Extruded Mg-Li-Al Alloys of α and α+ β Phase Composition using ECAP Processing

Preparation and surface modification of submicron YAl2 particles by mixed milling with magnesium for fabricating YAl2p/MgLiAl composites

Superplasticity at Elevated Temperature of a Coarse‐Grained Mg–Li Alloy

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