期刊
SCIENTIFIC REPORTS
卷 9, 期 -, 页码 -出版社
NATURE PUBLISHING GROUP
DOI: 10.1038/s41598-018-38420-7
关键词
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资金
- National Key Research and Development Program of China [2016YFB0301101, 2017YFB0305504]
- Fundamental Research Funds for the Central University [N160904001]
- Key Laboratory of Superlight Materials and Surface Technology (Harbin Engineering University), Ministry of Education
- Doctoral Scientific Research Foundation of Liaoning Province [201601219]
Mg-7Zn-5Gd-0.6Zr (wt%) alloy strengthened with quasicrystal phase (I-Mg(3)Z(6)Gd phase) is prepared through hot extrusion and subsequent heat treatments. The low temperature (range from 25 degrees C to 250 degrees C) superplastic deformation behavior of the as-extruded, aging treated (T5) and solution and aging treated (T6) alloys are investigated. The results reveal that a superior superplastic elongation of 863% is obtained at 250 degrees C and strain rate of 1.67 x 10(-3)s(-1) and the elongation of this alloy increases with the increasing tensile temperature. Detailed microstructural analyses show that I-Mg3Zn6Gd phase and W-Mg3Gd2Zn3 phase are crushed into small particles during extrusion. A high density of nanoscale I-phase precipitates after T5 treatment. Dynamic recrystallization occurs in as-extruded Mg-7Zn-5Gd-0.6Zr alloy. The T5-treated Mg-7Zn-5Gd-0.6Zr alloy shows a relatively weak basal texture intensity, a large number fraction of high angle boundaries and a very finer grain structure (3.01 mu m). During superplastic deformation, the nanoscale I-phase is slightly elongated and the microstructure is still equiaxed grains. The superplastic mechanism of the alloy is grain boundary sliding (GBS) accommodated by dislocation movement and static recrystallization. The cavity nucleation at the nanoscale I-phase/alpha-Mg matrix boundaries or grain boundaries and the cavity stringer formation leads to final fracture.
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