In Situ Scanning Electron Microscopy Observations of Contraction Twinning and Double Twinning in Extruded Mg-1Mn (wt.%)

A. Chakkedath, C. J. Boehlert

    Research output: Research - peer-reviewArticle

    • 1 Citations

    Abstract

    The tensile deformation mechanisms of an extruded Mg-1Mn (wt.%) alloy at 323 K (50°C) was investigated by a combination of in situ tensile testing and electron backscatter diffraction analysis. The strong basal texture of the material resulted in placing the c-axis of most of the grains under compression during tensile loading parallel to the extrusion axis. Basal, prismatic, and pyramidal 〈c+a〉 slip activity was observed along with $$ \left\{ {10\overline{1}2} \right\} $$101¯2 extension twinning. However, $$ \left\{ {10\overline{1}1} \right\} $$101¯1 contraction twinning dominated the deformation. Although contraction twinning and pyramidal 〈c+a〉 slip both allow for c-component deformation, contraction twinning was preferred over pyramidal 〈c+a〉 slip, and this was expected to be due to the lower critical resolved shear stress (CRSS) value for the former mechanism at ambient temperatures. The contraction twins evolved into $$ \left\{ {10\overline{1}1} \right\} - \left\{ {10\overline{1}2} \right\} $$101¯1-101¯2 double twins with an increase in strain. The propensity of double twins to form shear bands due to shear localization within the double twinned region, which eventually resulted in cracks, led to the failure of the material. The shear localization in the double twins was expected to be due to the enhanced activity of basal slip in the twinned volume. The observations from the present study suggest that contraction twinning may play a critical role in the limited cold formability of magnesium and its alloys.

    LanguageEnglish (US)
    Pages1748-1760
    Number of pages13
    JournalJOM
    Volume67
    Issue number8
    DOIs
    StatePublished - Jun 5 2015

    Profile

    Twinning
    Scanning electron microscopy
    Shear bands
    Tensile testing
    Formability
    Magnesium alloys
    Electron diffraction
    Extrusion
    Magnesium
    Shear stress
    Compaction
    Textures
    Cracks
    Temperature

    ASJC Scopus subject areas

    • Engineering(all)
    • Materials Science(all)

    Cite this

    In Situ Scanning Electron Microscopy Observations of Contraction Twinning and Double Twinning in Extruded Mg-1Mn (wt.%). / Chakkedath, A.; Boehlert, C. J.

    In: JOM, Vol. 67, No. 8, 05.06.2015, p. 1748-1760.

    Research output: Research - peer-reviewArticle

    @article{eced24e37700468a8e62a7dface6fb4b,
    title = "In Situ Scanning Electron Microscopy Observations of Contraction Twinning and Double Twinning in Extruded Mg-1Mn (wt.%)",
    abstract = "The tensile deformation mechanisms of an extruded Mg-1Mn (wt.%) alloy at 323 K (50°C) was investigated by a combination of in situ tensile testing and electron backscatter diffraction analysis. The strong basal texture of the material resulted in placing the c-axis of most of the grains under compression during tensile loading parallel to the extrusion axis. Basal, prismatic, and pyramidal 〈c+a〉 slip activity was observed along with $$ \left\{ {10\overline{1}2} \right\} $$101¯2 extension twinning. However, $$ \left\{ {10\overline{1}1} \right\} $$101¯1 contraction twinning dominated the deformation. Although contraction twinning and pyramidal 〈c+a〉 slip both allow for c-component deformation, contraction twinning was preferred over pyramidal 〈c+a〉 slip, and this was expected to be due to the lower critical resolved shear stress (CRSS) value for the former mechanism at ambient temperatures. The contraction twins evolved into $$ \left\{ {10\overline{1}1} \right\} - \left\{ {10\overline{1}2} \right\} $$101¯1-101¯2 double twins with an increase in strain. The propensity of double twins to form shear bands due to shear localization within the double twinned region, which eventually resulted in cracks, led to the failure of the material. The shear localization in the double twins was expected to be due to the enhanced activity of basal slip in the twinned volume. The observations from the present study suggest that contraction twinning may play a critical role in the limited cold formability of magnesium and its alloys.",
    author = "A. Chakkedath and Boehlert, {C. J.}",
    year = "2015",
    month = "6",
    doi = "10.1007/s11837-015-1478-5",
    volume = "67",
    pages = "1748--1760",
    journal = "JOM",
    issn = "1047-4838",
    publisher = "Minerals, Metals and Materials Society",
    number = "8",

    }

    TY - JOUR

    T1 - In Situ Scanning Electron Microscopy Observations of Contraction Twinning and Double Twinning in Extruded Mg-1Mn (wt.%)

    AU - Chakkedath,A.

    AU - Boehlert,C. J.

    PY - 2015/6/5

    Y1 - 2015/6/5

    N2 - The tensile deformation mechanisms of an extruded Mg-1Mn (wt.%) alloy at 323 K (50°C) was investigated by a combination of in situ tensile testing and electron backscatter diffraction analysis. The strong basal texture of the material resulted in placing the c-axis of most of the grains under compression during tensile loading parallel to the extrusion axis. Basal, prismatic, and pyramidal 〈c+a〉 slip activity was observed along with $$ \left\{ {10\overline{1}2} \right\} $$101¯2 extension twinning. However, $$ \left\{ {10\overline{1}1} \right\} $$101¯1 contraction twinning dominated the deformation. Although contraction twinning and pyramidal 〈c+a〉 slip both allow for c-component deformation, contraction twinning was preferred over pyramidal 〈c+a〉 slip, and this was expected to be due to the lower critical resolved shear stress (CRSS) value for the former mechanism at ambient temperatures. The contraction twins evolved into $$ \left\{ {10\overline{1}1} \right\} - \left\{ {10\overline{1}2} \right\} $$101¯1-101¯2 double twins with an increase in strain. The propensity of double twins to form shear bands due to shear localization within the double twinned region, which eventually resulted in cracks, led to the failure of the material. The shear localization in the double twins was expected to be due to the enhanced activity of basal slip in the twinned volume. The observations from the present study suggest that contraction twinning may play a critical role in the limited cold formability of magnesium and its alloys.

    AB - The tensile deformation mechanisms of an extruded Mg-1Mn (wt.%) alloy at 323 K (50°C) was investigated by a combination of in situ tensile testing and electron backscatter diffraction analysis. The strong basal texture of the material resulted in placing the c-axis of most of the grains under compression during tensile loading parallel to the extrusion axis. Basal, prismatic, and pyramidal 〈c+a〉 slip activity was observed along with $$ \left\{ {10\overline{1}2} \right\} $$101¯2 extension twinning. However, $$ \left\{ {10\overline{1}1} \right\} $$101¯1 contraction twinning dominated the deformation. Although contraction twinning and pyramidal 〈c+a〉 slip both allow for c-component deformation, contraction twinning was preferred over pyramidal 〈c+a〉 slip, and this was expected to be due to the lower critical resolved shear stress (CRSS) value for the former mechanism at ambient temperatures. The contraction twins evolved into $$ \left\{ {10\overline{1}1} \right\} - \left\{ {10\overline{1}2} \right\} $$101¯1-101¯2 double twins with an increase in strain. The propensity of double twins to form shear bands due to shear localization within the double twinned region, which eventually resulted in cracks, led to the failure of the material. The shear localization in the double twins was expected to be due to the enhanced activity of basal slip in the twinned volume. The observations from the present study suggest that contraction twinning may play a critical role in the limited cold formability of magnesium and its alloys.

    UR - http://www.scopus.com/inward/record.url?scp=84938964137&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84938964137&partnerID=8YFLogxK

    U2 - 10.1007/s11837-015-1478-5

    DO - 10.1007/s11837-015-1478-5

    M3 - Article

    VL - 67

    SP - 1748

    EP - 1760

    JO - JOM

    T2 - JOM

    JF - JOM

    SN - 1047-4838

    IS - 8

    ER -