Research ArticleMATERIALS SCIENCE

Direct imaging of short-range order and its impact on deformation in Ti-6Al

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Science Advances  13 Dec 2019:
Vol. 5, no. 12, eaax2799
DOI: 10.1126/sciadv.aax2799
  • Fig. 1 TEM bright-field imaging of deformed Ti-6Al with different thermal history.

    (A) Sample aged to promote SRO; the blue arrows mark the in-band dislocation pairs. (B) Sample quenched after homogenization.

  • Fig. 2 Energy-filtered DF imaging of SRO domains.

    (A) The energy-filtered DF image from superlattice diffraction shows distinguishable SRO domains. (B) Enlarged DF image with identified SRO domains marked by the red circles; the circles are scaled larger than the measured radius. (C) Energy-filtered [21¯1¯0] diffraction pattern. The orange arrows indicate the positions of the diffuse DO19 superlattice diffraction peaks. The red circle marks the objective aperture position used in (A). (D) Size distribution of the identified SRO domains from three DF images (enlarged images are shown in fig. S7); the error bars were assigned according to the SD among three similar images.

  • Fig. 3 Comparison of the mechanical response of Ti-6Al in the quenched and SRO-aged conditions.

    (A) True stress-strain curves of the quenched and SRO-aged samples. (B) Enlarged true stress-strain curves near yielding of both materials; the 0.2% offset yield strength is marked on the plot. (C and D) Indentation stress-strain curves of as-quenched sample and SRO-aged sample, respectively. Different indentations are marked with different colors.

  • Fig. 4 Energy-filtered DF images of planar dislocation slip bands.

    (A) Bright-field image showing the relation of a slip band and the imaging area. The slip band is marked and shows weak-fringing contrast in the zoomed-in image. (B) Energy-filtered DF image at the same position of (A) showing the lack of contrast in the slip band.

  • Fig. 5 Diffraction analysis of TEM in situ compression test on a nanopillar made from an SRO-aged sample.

    (A) DF image, diffraction pattern, and superlattice diffraction intensity line plot from before the in situ compression test. The position of the line plot is marked on the diffraction pattern. (B) DF image, diffraction pattern, and superlattice diffraction intensity line plot from after the in situ compression test. The position of the line plot is marked on the diffraction pattern. After the deformation, the diffuse superlattice peaks decreased beneath the noise level, presumably caused by the destruction of SRO at the tip region due to the dislocation activities.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/12/eaax2799/DC1

    Supplementary Text

    Fig. S1. Diffraction contrast showing the destruction of SRO clusters in a slip band using QED.

    Fig. S2. Dislocation slip trace analysis conducted with HRSTEM imaging.

    Fig. S3. GPA of an SRO-aged sample and a high-purity Ti sample.

    Fig. S4. Cross-section thickness measurement of the TEM sample imaged in Fig. 2.

    Fig. S5. Parameter optimization of the SRO domain identification algorithm.

    Fig. S6. Diffraction patterns and DF images of samples with different thermal histories.

    Fig. S7. Energy-filtered DF images showing SRO-enhanced domains.

    Movie S1. Schematic of the in situ pillar compression test.

    Movie S2. One example of the in situ pillar compression.

  • Supplementary Materials

    The PDFset includes:

    • Supplementary Text
    • Fig. S1. Diffraction contrast showing the destruction of SRO clusters in a slip band using QED.
    • Fig. S2. Dislocation slip trace analysis conducted with HRSTEM imaging.
    • Fig. S3. GPA of an SRO-aged sample and a high-purity Ti sample.
    • Fig. S4. Cross-section thickness measurement of the TEM sample imaged in Fig. 2.
    • Fig. S5. Parameter optimization of the SRO domain identification algorithm.
    • Fig. S6. Diffraction patterns and DF images of samples with different thermal histories.
    • Fig. S7. Energy-filtered DF images showing SRO-enhanced domains.
    • Legends for movies S1 and S2

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Schematic of the in situ pillar compression test.
    • Movie S2 (.mp4 format). One example of the in situ pillar compression.

    Files in this Data Supplement:

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