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研究了Fe与Al混合粉在放电等离子烧结(SPS)作用下的反应扩散行为。采用X射线衍射及扫描电镜对显微组织演化进行了分析,并揭示了烧结动力学行为。结果表明在SPS温度773~873 K下,Fe2Al5为反应中间相。尽管电流可以提高材料扩散速度,球磨处理可在粉体中产生大量点阵缺陷及晶粒边界,使反应动力学速度得到提高。球磨后,相变动力学速度从球磨前的4.56×10~(-3)提高到0.207。而且,本研究揭示了焦耳热产生行为。作为电流通道,阻抗是重要的焦耳热源。SPS过程中粉末颗粒、模具、冲头、石墨纸之间界面阻抗是焦耳热产生的重要来源。
The reaction diffusion behavior of mixed powders of Fe and Al under the action of spark plasma sintering (SPS) was studied. The microstructure evolution was analyzed by X-ray diffraction and scanning electron microscopy, and the sintering kinetic behavior was revealed. The results show that Fe2Al5 is the reaction mesophase at SPS temperature of 773 ~ 873 K. Although the current can improve the material diffusion rate, ball milling process can produce a large number of lattice defects in the powder and grain boundaries, the reaction kinetic rate is improved. After ball milling, the kinetics of phase transformation increased from 4.56 × 10 -3 before rolling to 0.207. Moreover, this study reveals the Joule heating behavior. As a current path, impedance is an important Joule heat source. SPS process powder particles, die, punch, graphite paper interface impedance is an important source of Joule heat.