Deformation behaviour of Mg–Li alloys at elevated temperatures

Trojanová, Zuzanka; Drozd, Zdeněk; Lukáč, P.; Chmelı́k, František

doi:10.1016/j.msea.2005.08.088

Cited by 72 publications

(48 citation statements)

References 8 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: 76%

“…However, the sample after HPT carried out at lower temperature showed significantly better superplastic properties after ECAP than the other alloys [10]. On the other hand, the method has limitations concerning the size of samples and inhomogeneity of deformation.…”

Section: Resultsmentioning

confidence: 94%

“…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: 98%

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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: 76%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 98%

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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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“…Cross-slip and climb of dislocations may be responsible for the softening in the hightemperature plastic deformation process, especially for the single-phase Mg-Li alloy. 15) However, during deformation of dual phase Mg-Li alloy polycrystals, another factor of codeformation between and phases is assumed. The f0001gh11 " 2 20i slip system in the phase and f110gh111i slip system in the phase can match with each other, according to the calculation of crystallography of the bcc/hcp transformation in the Mg-Li alloy that had been reported.…”

Section: Analysis Of the Extruded Structurementioning

confidence: 99%

Microstructure and Mechanical Properties of the As-Cast and Extruded Mg-(6-11)Li-3Al-Ce-Ca Alloys

Cheng

Cao

et al. 2010

Mater. Trans.

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Samples of (A) Mg-6.86Li-3.02Al-1.12Ce-0.7Ca, (B) Mg-8.15Li-3.07Al-1.12Ce-0.72Ca and (C) Mg-10.54Li-3.54Al-1.23Ce-0.94Ca alloys are prepared by casting and extrusion process. The microstructure and mechanical properties of alloys are characterized. The results indicate that the as-cast specimens of (A) and (B) have þ dual phase structure and the as-cast (C) alloy has phase (Li), þ eutectic structure. Bulk and rod-like Al 2 Ce and Al 2 Ca compounds are found in matrix and boundaries in all the alloys. The orientation relationship between a type of Al 2 (Ce, Ca) phase and the phase is confirmed, i.e., ½ " 1 112 == ½7 " 2 2 " 5 53, ð1 " 1 11Þ == ð01 " 1 1 " 1 1Þ. For the extruded alloys, the microstructures are refined and the phase has the effect of coordination during deformation. The long rod-like and bulk compounds become short rods and fine clumps distributing evenly in the extruding direction. The microstructure of extruded Mg-10.54Li-3.54Al-1.23Ce-0.94-Ca alloy testifies the existence of the eutectic structure. The tensile strength and yield strength of Mg-6.86Li-3.02Al-1.12Ce-0.7Ca (UTS: 12.5%, YS: 36%) and Mg-8.15Li-3.07-Al-1.12Ce-0.72Ca (UTS: 24%, YS: 46%) alloys have improved after extruding process.

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“…[3][4][5] However, the application of Mg-Li alloys is restricted in practice due to undesirable properties, mainly poor corrosion and wear resistance. [6][7][8][9] Surface treatment, specifically coating, is an effective way to improve corrosion resistance and wear resistance of Mg alloys.…”

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confidence: 99%

Ultrasonic-Assisted Electroless Ni-P Plating on Dual Phase Mg-Li Alloy

Zou

Zhang

Liu

et al. 2014

J. Electrochem. Soc.

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An ultrasonic-assisted method for electroless Ni-P plating on dual-phase Mg-Li alloy is proposed. Environmentally-friendly Ce(NO 3 ) 3 -KMnO 4 solution was successfully applied for the pre-treatment. Uniform and compact Ni-P coatings with fine structures have been successfully obtained. The Ni-P coatings are mixed with amorphous-crystalline features and well adhered to the substrates. The corrosion resistances were investigated by electrochemical impedance spectroscopy, open circuit potential, potentiodynamic polarization and hydrogen evolution tests. The results indicate that ultrasonic processing significantly improves the corrosion resistance of Ni-P coatings due to the formation of uniform, dense and fine structures, which strengthen the passive film. Magnesium-lithium (Mg-Li) alloys are the lowest in density of metallic structural materials.1 Mg-Li alloys have excellent properties, such as high specific strength, good formability, damping capacity, impact resistance and energetic particle penetration tolerances.1,2 These properties provide Mg-Li alloys with a great potential for various applications, especially for transportation, in the aerospace industry and for electronic components.3-5 However, the application of Mg-Li alloys is restricted in practice due to undesirable properties, mainly poor corrosion and wear resistance.6-9 Surface treatment, specifically coating, is an effective way to improve corrosion resistance and wear resistance of Mg alloys. Among them, nickel-phosphorous (Ni-P) plating remains of high interest because of its unique advantages, including good corrosion resistance, wear resistance, lubricity, acceptable ductility, electric conduction and high hardness. 26 However, electroless Ni-P plating on Mg-Li base alloys, specifically on dual phase Mg-8 wt%Li base alloys, is much more difficult than on other Mg base alloys because the standard electrode potential of Li (−3.045 V vs SHE) is lower than that of Mg (−2.37 V vs SHE), making the alloy extremely susceptible to galvanic corrosion. This results in an unattractive appearance of plating and in the degradation of mechanical properties.Electroless nickel plating is an autocatalytic reaction for deposition of nickel on a substrate. 27 There are two main methods for electroless nickel plating on magnesium alloys, i.e. direct electroless nickel plating 9,28,29 and zinc immersion. 8,30-32 Direct electroless nickel plating has the advantages of simplicity and suitability for magnesium alloys with high aluminum content. Nevertheless, the main disadvantage of this method is the use of hexavalent chromium compounds [Cr(VI)] and hydrofluoric acid [HF] during the etching and conversion coating treatments. These materials are not friendly to the environment and increase the risk to people during operation. 8,9 The zinc immersion procedure is complicated and the step of plating copper with cyanide is poisonous to humans and the environment. In addition, common electroless nickel plating exhibits other drawbacks, such as energy consumption, fast ev...

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Deformation behaviour of Mg–Li alloys at elevated temperatures

Cited by 72 publications

References 8 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

Microstructure and Mechanical Properties of the As-Cast and Extruded Mg-(6-11)Li-3Al-Ce-Ca Alloys

Ultrasonic-Assisted Electroless Ni-P Plating on Dual Phase Mg-Li Alloy

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