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2019年材料學院系列學術報告(四)

  報告題目:Quantitative Electron Microscopy For Aluminum Alloys As Light-Weight Industry Materials 

  報告時間:2019年5月15日(周三)9:00-10:30

  報告地點:北辰校區理學院416報告廳

  報告嘉賓:陳江華教授,湖南大學材料科學與工程學院

 

  報告摘要:Developments of high-strength aluminum alloys have always faced a difficult problem: owing to their small size, the early-stage strengthening precipitates are difficult to characterize in terms of composition, structure and evolution. Here we employ atomic-resolution transmission electron microscopy (TEM) imaging and first-principles energy calculations to address these problems. Recent years, we have investigated tens of typical high strength aluminum alloys, such as 2xxx (AlCu, AlCuMg and AlCuLiMg), 6xxx (AlMgSi and AlMgSiCu) and 7xxx (AlZnMg and AlZnMgCu) alloys, with different compositions and with varying thermal processes for understanding their property-structure-process correlations. Using aberration-corrected high-resolution TEM (HRTEM) and aberration-corrected scanning TEM (STEM), much of our attention has been paid to revisit the strengthening precipitates in these important alloys and to clarify the controversies left in the past about their precipitation behaviors. Our study demonstrates the followings: (1) Atomic-resolution imaging in STEM can provide straightforward structure models at the atomic-scale, whereas atomic-resolution imaging in HRTEM with rapid quantitative image simulation analysis can provide the refined structures with high precision beyond the resolution limitation of the microscope. The combination of the two techniques can be more powerful in solving difficult structure problems in materials science. (2) Most of the early-stage precipitates in aluminum alloys are highly dynamic in both composition and structure. Typically, having their characteristic genetic skeletons to guide their evolution, these dynamic precipitates initiate, mature and grow with thermal aging following characteristic evolution paths. The fine precipitation scenarios revealed in our studies are rather different from previous understandings in the textbooks and literatures published thus far.

 

  嘉賓簡介

  陳江華,教授,博導,湖南大學材料科學與工程學院院長,教育部“長江學者”特聘教授。陳江華在材料科學研究上取得了較突出成果。在系列鋁合金微觀結構研究方面的成果發表在Science, Acta Materialia, Scripta Materialia等著名雜志;在電子顯微學理論與方法研究方面取得多項進展,成果發表于Nature materials, Ultramicroscopy, Micron等專業雜志;在鋁合金熱處理工藝研發方面形成了國內核心專利。陳江華在湖南大學建成了國際先進、有特色的原子成像技術平臺;在普通場發射透射電鏡的基礎上,成功實現出射波函數重構(EWR)原子成像技術和高角環形暗場掃描透射電(HAADF-STEM)原子成像技術。他是教育部首批黃大年式教師團隊負責人,承擔了科技部973課題、國家自然科學基金重大科研儀器研究項目、國防基礎研究課題、高鐵材料重大橫向課題等科研任務;是中國儀器儀表學會儀表功能材料學會副理事長,并擔任《金屬學報》英文版等多個國內外雜志編委。

 

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