Improvement of formability and mechanical properties of magnesium alloys via pre-twinning: A review

Song, Bo; Guo, Ning; Liu, Tingting; Yang, Qingshan

doi:10.1016/j.matdes.2014.05.034

Cited by 173 publications

(37 citation statements)

References 63 publications

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“…With an increase in the basal Schmid factor and activation of the basal slip system, an angle is formed between the basal planes of the grains and the bending direction so that the c-axis becomes inclined from the ND towards the RD. Thus, it was suggested that the weaker (0002) basal texture could result in a higher Schmid factor of the basal slip and thus leads to the lower yield strength and higher ductility 33,34 .…”

Section: Resultsmentioning

confidence: 99%

Effect of Multi-Pass Bending Deformation on Microstructure Evolution and Mechanical Properties of AZ31 Alloy Sheet

Yang

Dai

et al. 2016

Mat. Res.

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The rolled AZ31 Mg alloy sheets were processed by multi-pass bending (MPB) process at room temperature and followed by annealing treatment. Mechanical properties of the as-received and MPB sheets in annealed conditions were examined based on the concurrent microstructure and texture evolution. The results show that the room temperature ductility of the Mg sheets was improved by multi-pass bending process. Moreover, the (0002) basal texture was drastically weakened. Enhanced the ambient mechanical properties, such as lower yield strength and larger uniform elongation, were fabricated by MPB path due to the weak basal texture. The microstructure and mechanical responses were characterized and discussed.

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Section: Resultsmentioning

confidence: 99%

Effect of Multi-Pass Bending Deformation on Microstructure Evolution and Mechanical Properties of AZ31 Alloy Sheet

Yang

Dai

et al. 2016

Mat. Res.

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“…6. The randomization of basal texture would contribute to the increment of ductility, since more deformation modes of basal slips and twinning can be activated [36,37]. The bimodal grain size would allow some easy slips in fine-grained regions, but delay slipping in the coarse-grained regions to the higher stress level.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

On the microstructure and mechanical property of as-extruded Mg-Gd-Y-Zn alloy with Sr addition

Liu

Diao

Chai

et al. 2017

Materials Science and Engineering: A

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In this study, microstructure evolutions of 0.2, 0.6) alloys (named as sample 0Sr, 0.2Sr, 0.6Sr) during heat-treatment and extrusion were investigated. As-cast sample 0Sr contains typical long period stacking ordered (LPSO) phases and Mg 3 RE. With Sr addition, amounts of LPSO phases decrease and are gradually replaced by the Mg 17 Sr 2 phases. After homogenization and annealing treatment, profuse strip LPSO phases readily precipitate in grain interiors of sample 0Sr, while only Mg 17 Sr 2 and Mg 3 RE phases are detected in samples 0.2Sr and 0.6Sr. It suggests that the Sr addition would inhibit LPSO phases. After extrusion, the bimodal grain structures, the bulk and strip LPSO phases are detected in sample 0Sr, which can contribute to providing strengthening and extra strain hardening. In as-extruded sample 0.2Sr, finer recrystallized grain size, bulk Mg 17 Sr 2 and LPSO phases (micron-scale) and Mg 5 RE phase (nano-scale) are found due to the pre-annealing treatment. However, lower amounts of both nano-sized and macro-sized LPSO phases lead to the low ultimate strength (300 MPa). In sample 0.6Sr, the strip LPSO phases are readily formed even though the length and total amounts of LPSO phases decrease.More bulk Mg 17 Sr 2 phases and LPSO phases are also precipitated, which lead to the more superior yield and ultimate strengths of 0.6Sr sample under higher temperature, as compared with the 0Sr sample.2

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“…Thus, to further improve mechanical properties of magnesium fine tubes, the design of fine and dense twin lamellae should be studied in future work. The twin boundaries was shown to generate a refinement hardening effect in magnesium tubes [266]. So the twin boundary hardening, spacing of twin lamellae and average twin size should be studied in future work.…”

Section: Magnesium Alloy Tubesmentioning

confidence: 97%

“…The six equivalent twin variants were listed in Table 2.3 [266]. The orientation of twins can be defined by the selected twin variants.…”

Section: Texture Of Mg Alloysmentioning

confidence: 99%

“…The number of independent slip systems is limited in Mg alloys due to their hexagonal close packed structure especially at low temperatures. Due to the limited number of the slip systems and in order to meet the von Mises criterion, Mg alloys exhibit a strong propensity for mechanical twinning [266,338,339]. The activation of twinning during deformation has a large effect on texture evolution and flow stress due to lattice reorientation, e.g., the lattice will rotate by 86.3° through {101 ̅ 2} twinning [65].…”

Section: Introductionmentioning

confidence: 99%

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Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

Yao-wu¹

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Fine tube stents are used for maintaining localised flow in stenotic blood vessels. Elasticity and plasticity for expansion, rigidity for resisting bending under force and strength to prevent unexpected failure, are required properties of the tubes from which these stents are formed. Biomedical metastable β titanium alloys have been developed as implant materials for a large number of biomedical applications due to a combination of favourable characteristics, e.g. good biocompatibility, excellent toughness and corrosion resistance. A metastable β alloy, Ti-25Nb-3Mo-3Zr-2Sn, has been developed without toxic alloying elements, which is a promising candidate material for stent applications. Metallic materials used for stents are commonly not biodegradable and implanted in the vessel permanently, which may provoke in-stent restenosis and stent thrombosis. In order to remove the implanted materials after service, biodegradable materials, absorbed by the body slowly, are also a field of research interest. Magnesium alloys have been used in studies for biomedical stent applications as a new biodegradable material. Magnesium stents can reopen the blocked blood vessels temporarily before degrading in physiological environments. In addition to the biodegradable characteristics, their mechanical properties are reasonable. The Mg-3Al-1Zn (AZ31) alloy is the subject of some research on the processing of biomedical magnesium alloys as it is a commonly available commercial alloy. Consequently, the Ti-25Nb-3Mo-3Zr-2Sn alloy and the AZ31 magnesium alloy have been used in this thesis to investigate the evolution of mechanical properties and microstructure in the processing of fine tubes.The deformation mechanisms during cold deformation of metastable β titanium alloys are mainly associated with martensitic phase transformations and mechanical twinning. It has been reported that stress-induced phase transformations and {112}〈111〉, {332}〈113〉 twinning modes may be activated under different stress states in metastable β titanium alloys. They can exhibit varying elasticity, Young's modulus and strain hardening behaviour. Because the martensitic start temperature is below room temperature for most metastable β titanium alloys, the α″ martensitic transformation can easily occur under a small amount of external stress. Mechanical twins were reported to hinder slip and dislocation motion thereby increasing the strain hardening rate. The development of β and α″ texture during processing is another critical influence on the mechanical properties of fine tubes. Therefore, studies on the martensitic transformation, mechanical twins and texture evolution is of significance in order to understand the processing of β titanium fine tubes.ii Magnesium alloys deform through the formation of a large amount of mechanical twins due to the relatively low critical stress to activate twinning in comparison with 〈 + 〉 slip. There are typically two primary mechanical twinning modes for magnesium alloys, {101 ̅ 2} extension twins and {101 ̅ 1} cont...

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Improvement of formability and mechanical properties of magnesium alloys via pre-twinning: A review

Cited by 173 publications

References 63 publications

Effect of Multi-Pass Bending Deformation on Microstructure Evolution and Mechanical Properties of AZ31 Alloy Sheet

Effect of Multi-Pass Bending Deformation on Microstructure Evolution and Mechanical Properties of AZ31 Alloy Sheet

On the microstructure and mechanical property of as-extruded Mg-Gd-Y-Zn alloy with Sr addition

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

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