Twinning-induced softening in polycrystalline AM30 Mg alloy at moderate temperatures

Jiang, Lan; Jonas, John J.; Luo, Alan A.; Sachdev, Anil K.; Godet, Stéphane

doi:10.1016/j.scriptamat.2005.11.029

Cited by 270 publications

(92 citation statements)

References 7 publications

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“…This characteristic is the opposite of that of AZ 31B magnesium alloy, in which the n value decreases linearly as ε increases from 1.0 × 10 −5 s −1 to 1.0 × 10 −2 s −1 at RT 35) . This behavior has also been observed in AM30 magnesium alloy tested at 298 K, and the authors claimed that it was caused by the twinning-induced softening effect in deformed HCP-structural alloy 36) . However, the HR LZ141 is a BCC structural alloy, instead of an HCP one, and no twinning is observed in deformed specimens.…”

Section: Discussion On Tensile and Charpy Impact Properties Of Hr Lz1mentioning

confidence: 61%

Effects of Strain-Rate and Temperature on Mechanical Properties of Hot-Rolled Mg-14.3Li-0.8Zn β-Phase Alloy

Chien

Yang

2016

Mater. Trans.

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The hot-rolled Mg-14.3Li-0.8Zn (HR LZ141) alloy exhibits anisotropic tensile properties with an average value of the normal anisotropic parameter, r avg , of 0.6. From microstructural observation, it is proposed that the mechanical bering, which is caused by the preferred alignment of the small α-phase particles in the rolling direction, results in this anisotropic property. Both strain rate ε and temperature T in uence the tensile properties. At 6.67 × 10 −5 s −1 to 6.67 × 10 −2 s −1 and room temperature, the tensile properties are all linear and sensitive to the log-scale ε . The strain-rate sensitivity exponent, m, is 0.055 at all testing ε . The work-hardening exponent, n, is positive, and the higher the ε is, the larger the n-value is, but the increase in the n-value is quite low for ε < 3.33 × 10 −4 s −1 and ε > 6.67 × 10 −3 s −1. The yield point phenomenon appears in σ-ε curves at room temperature when ε = 6.67 × 10 −5 s −1 , and at 343 K when ε = 3.33 × 10 −3 s −1. The work-softening phenomenon occurs at T ≥ 343 K with ε = 3.33 × 10 −3 s −1. The yield stress and UTS increase but the elongation decreases as the testing temperature decreases. The Charpy impact test indicates that different notch orientations in uence the impact energy due to the formation of mechanical bering, and the result of impact energy vs. temperature shows no signi cance of transition temperature.

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Section: Discussion On Tensile and Charpy Impact Properties Of Hr Lz1mentioning

confidence: 61%

Effects of Strain-Rate and Temperature on Mechanical Properties of Hot-Rolled Mg-14.3Li-0.8Zn β-Phase Alloy

Chien

Yang

2016

Mater. Trans.

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“…Theoretical ORs of f10 1 11g twin and f10 1 13g twin are 56 h11 2 20i and 64 h11 2 20i respectively, and the double twinning of them will lead to the ORs of 38.7 h11 2 20i and 22 h11 2 20i. 3,8,9) The misorientation data in Fig. 2 reveal that most misorientation angles are larger than those due to double twinning (38 and 22 ), but smaller than those of two types of compression twins (56 and 64 ).…”

Section: Determination Of Twin Orientation and Orientationmentioning

confidence: 95%

“…Recently, EBSD technique has been used to analyze compression twins through the determination of the twin orientation relationships (OR). 8,9) To date, the analysis on compression twin has been less reported than that of tension twin, and the variety of compression twin types as well as the condition of double twinning is still not clearly understood. This is because the compression twin analysis has three challenges: (1) The compression twins are very thin in nature (normally less than 1 mm), it is hard to confirm their types on a large scale; (2) unlike the very mobile boundaries of tension twins which leads to stable OR of 86.3 h11 2 20i, the immobile twin boundaries of the compression twins and their unstable orientation against basal slip or tension twinning can cause frequent change in twin orientation; (3) In some cases, it is not easy to exactly confirm the twin forms by detecting the OR, for example, the OR of 38.7 h11 2 20i for double twinning is similar to the OR of 41 h11 2 20i for f10 1 15g twins.…”

Section: Introductionmentioning

confidence: 99%

Analyses on Compression Twins in Magnesium

et al. 2008

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The orientation relationships between the compression twins and their matrices in magnesium were investigated using EBSD technique. Schmid factor analyses were applied to determine the orientation dependency of compression twins and the condition for double twinning. Results show that thin compression twin bands of f10 1 11g type lose easily their exact twin relation of 56 h11 2 20i to $40 h11 2 20i due to the instability of twin orientation and immobility of twin boundaries. And the basal orientation with TD-rotation tends to induce tension twinning in compression twins.

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“…It is observed that {10 1} contraction twinning and double twinning can be activated in the RD (Fig. 4), and they increased linearly with the increase of Q. Decreasing strain hardening resulted from the formation of contraction and double twins due to the reduction of the strain hardening index, n (Jiang, Jonas, Luo, Sachdev, & Godet, 2006). Extension twinning may also be activated in the TD.…”

Section: Influence Of Twinning On Mechanical Behaviourmentioning

confidence: 97%

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

Yao-wu

Kent

Wang

et al. 2014

Journal of the Mechanical Behavior of Biomedical Materials

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The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents, Journal of the Mechanical Behavior of Biomedical Materials, http://dx.doi.org/10. 1016/j.jmbbm.2014.07.026 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractMg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a crosssectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24.Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at an ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes.

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Twinning-induced softening in polycrystalline AM30 Mg alloy at moderate temperatures

Cited by 270 publications

References 7 publications

Effects of Strain-Rate and Temperature on Mechanical Properties of Hot-Rolled Mg-14.3Li-0.8Zn β-Phase Alloy

Effects of Strain-Rate and Temperature on Mechanical Properties of Hot-Rolled Mg-14.3Li-0.8Zn β-Phase Alloy

Analyses on Compression Twins in Magnesium

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

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