科研之友
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摘要
In the present work, we investigated the influence of deformation temperature on the formation of a bimodal microstructure and tensile properties of a Mg-9Al-1Zn (AZ91) alloy processed by a single pass hard plate rolling (HPR) with a thickness reduction of 55% followed by a short time annealing. Micro-structural examinations by electron backscatter diffraction (EBSD) reveal that there exists a narrow deformation temperature window, i.e. it is only feasible to achieve a desired bimodal grain structure in the AZ91 alloy when HPRed at similar to 350 degrees C. It is mainly because that partial dynamic recrystallization (DRX) occurs easily in the sample HPRed at similar to 350 degrees C, facilitating the formation of a bimodal microstructure consisting of coarse un-recrystallized grains (>similar to 70 mu m) and fine recrystallized grains (<similar to 5 mu m). In contrast, reducing deformation temperature to -300 degrees C results in a coarse unrecrystallized microstructure containing substantial sub structure, while elevating the deformation temperature to similar to 400 degrees C leads to an almost uniform recrystallized grain structure. Especially, the formation mechanism for the bimodal grain structure at the optimum deformation temperature is explored in terms of Schmidt factors analysis for basal slips (SFbasal) for grains of different size scales. Moreover, the 350 degrees C HPRed AZ91 sample exhibits a better combination of strength (ultimate tensile strength = similar to 374 MPa) and ductility (elongation = similar to 19.6%), as compared to the 300 and 400 degrees C samples. It is mainly attributed to the typical bimodal grain structure and the relatively high SFbasal featured by the fine recrystallized grains as well as the nanometer spherical particles distributing in fine grain interiors.
- 出版日期2018-10-15
- 单位吉林大学
