کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1450312 | 988730 | 2008 | 9 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: In situ X-ray synchrotron diffraction study of MgB2 synthesis from elemental powders In situ X-ray synchrotron diffraction study of MgB2 synthesis from elemental powders](/preview/png/1450312.png)
The kinetics of MgB2 synthesis is studied in situ by synchrotron X-ray diffraction, using pressed compacts of 200–400 μm magnesium powders mixed with three types of submicrometer, amorphous, high-purity boron powders. Reaction times for commercially available and plasma-synthesized boron powders decreases from 100 to 2 min as temperature increases from 670 to 900 °C. They can be described by diffusion-controlled models of a reacting sphere with kinetics characterized by diffusion coefficients increasing with temperature from 2 × 10−17 to 3 × 10−16 m2 s−1, with activation energies of 123–143 kJ mol−1. Plasma-synthesized boron powders doped with 7.4 at.% carbon show no significant differences in reaction kinetics as compared to undoped powders.
Journal: Acta Materialia - Volume 56, Issue 8, May 2008, Pages 1680–1688