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碳化硅纳米颗粒与第二相协同增强镁基复合材料的热变形行为及加工图

Hot Deformation Behavior and Processing Maps of SiC Nanoparticles and Second Phase Synergistically Reinforced Magnesium Matrix Composites.

作者信息

Nie Kaibo, Zhu Zhihao, Deng Kunkun, Wang Ting, Han Jungang

机构信息

College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China.

Shanxi key Laboratory of Advanced Magnesium-Based Materials, Taiyuan University of Technology, Taiyuan 030024, China.

出版信息

Nanomaterials (Basel). 2019 Jan 3;9(1):57. doi: 10.3390/nano9010057.

Abstract

Magnesium matrix composites synergistically reinforced by SiC nanoparticles and second phases were prepared by 12 passes of multi-pass forging, varying the temperature. The effects of grain refinement and the precipitates on the hot deformation behavior were analyzed. Deformation zones which could be observed in the fine-grained nanocomposite before hot compression disappeared, and the trend of streamlined distribution for the precipitated phases was weakened. At the same compression rate, as the compression temperature increased, the number of precipitated phases decreased, and the grain size increased. For fine-grained nanocomposites, after the peak stress, there was no obvious dynamic softening stage on the stress⁻strain curve, and then the steady stage was quickly reached. The critical stress of the fine-grained nanocomposites was lower than that of the coarse-grained nanocomposites, which can be attributed to the large amounts of precipitates and significantly refined grains. The deformation mechanism of the coarse-grained nanocomposite was controlled by dislocation climb resulting from lattice diffusion, while the deformation mechanism for the fine-grained nanocomposite was dislocation climb resulting from grain boundary slip. The activation energy of the fine-grained nanocomposite was decreased, compared with the coarse-grained nanocomposite. The area of the workability region for the fine-grained nanocomposite was significantly larger than that of the coarse-grained nanocomposite, and there was no instability region at a low strain rate (0.001⁻0.01 s) under all deformation temperatures. The optimal workability region was 573 K /0.001⁻0.01 s for the fine-grained nanocomposite, and the processing temperature was lower than the coarse-grained nanocomposite (623⁻673 K).

摘要

通过12道次多道次锻造并改变温度,制备了由SiC纳米颗粒和第二相协同增强的镁基复合材料。分析了晶粒细化和析出相对热变形行为的影响。在热压缩前的细晶纳米复合材料中可观察到的变形区消失,析出相的流线分布趋势减弱。在相同压缩速率下,随着压缩温度升高,析出相数量减少,晶粒尺寸增大。对于细晶纳米复合材料,在峰值应力之后,应力-应变曲线上没有明显的动态软化阶段,然后迅速进入稳态阶段。细晶纳米复合材料的临界应力低于粗晶纳米复合材料,这可归因于大量的析出相和显著细化的晶粒。粗晶纳米复合材料的变形机制由晶格扩散引起的位错攀移控制,而细晶纳米复合材料的变形机制是由晶界滑移引起的位错攀移。与粗晶纳米复合材料相比,细晶纳米复合材料的激活能降低。细晶纳米复合材料的可加工区域面积明显大于粗晶纳米复合材料,并且在所有变形温度下,在低应变速率(0.001-0.01 s)下没有不稳定区域。细晶纳米复合材料的最佳可加工区域为573 K/0.001-0.01 s,加工温度低于粗晶纳米复合材料(623-673 K)。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/252e/6359663/cedb222089d4/nanomaterials-09-00057-g001.jpg

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