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2019年材料学院系列学术报告(四)

  报告题目:Quantitative Electron Microscopy For Aluminum Alloys As Light-Weight Industry Materials 

  报告时间:2019年5月15日(周三)9:00-10:30

  报告地点:北辰校区理学院416报告厅

  报告嘉宾:陈江华传授,湖南大学材料科学与工程学院

 

  报告摘要: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.

 

  嘉宾概况

  陈江华,传授,博导,湖南大学材料科学与工程学院院长,教育部“长江学者”特聘传授。陈江华在材料科学研究上取得了较突出成果。在系列铝合金微观结构研究方面的成果发表在Science, Acta Materialia, Scripta Materialia等著名杂志;在电子显微学理论与方法研究方面取得多项进展,成果发表于Nature materials, Ultramicroscopy, Micron等专业杂志;在铝合金热处理工艺研发方面形成了国内核心专利。陈江华在湖南大学建成了国际先进、有特色的原子成像技术平台;在普通场发射透射电镜的基础上,成功实现出射波函数重构(EWR)原子成像技术和高角环形暗场扫描透射电(HAADF-STEM)原子成像技术。他是教育部首批黄大年式教师团队负责人,承担了科技部973课题、国家自然科学基金重大科研仪器研究项目、国防基础研究课题、高铁材料重大横向课题等科研任务;是中国仪器仪表学会仪表功能材料学会副理事长,并担任《金属学报》英文版等多个国内外杂志编委。

 

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