The effect of submicron SiC particles on the thermal stability of nanocrystalline AZ91 alloy
The effect of submicron SiC particles on the thermal stability of nanocrystalline AZ91 alloy
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DOI：
10.1016/j.jmrt.2022.11.147
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
Qian Su;Rongrong Wang;Huan Yu;Hang Li;Jixue Zhou;Dejin Wang;L. Hu
中科院分区：
文献类型：
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作者：
Qian Su;Rongrong Wang;Huan Yu;Hang Li;Jixue Zhou;Dejin Wang;L. Hu
纳米晶（NC）镁合金和复合材料由于具有出色的强度，在运输应用中具有提高能源效率的潜力。不幸的是，由于高温下晶粒生长而导致的软化将导致致命的失效。对NC SiCp/AZ 91复合材料进行了等温退火处理。研究了该合金的热稳定性，包括相变、晶粒长大、软化和强化机制。经673 K × 240 min退火处理后，AZ 91 - 15 vol.% SiCp复合材料从29.0 nm增加到53.1 nm。高分辨透射电子显微镜（HRTEM）证实了纳米级Mg 17 Al 12析出相与镁基体之间存在共格界面。纳米级Mg 17 Al 12析出相和尺寸为164 nm的亚微米SiC颗粒的弥散分布所产生的钉扎效应以及Al元素溶解所产生的拖曳效应是其优异热稳定性的原因。经退火处理后，AZ 91-xvol.% SiCp（x = 5，10和15）复合材料的压力分别为1.61GPa，1.48GPa和1.78GPa。取退火AZ 91 - 15 vol.%以SiCp复合材料为例，与球磨复合材料（硬度为1.82GPa）相比，未发现明显的软化现象，降低幅度为1.2%。非热敏性SiC颗粒和高热稳定性Mg基体是复合材料不软化的关键。
Nanocrystalline (NC) magnesium alloys and composites present potential for improving energy efficiency in transportation applications due to outstanding strength. Unfortunately, softening owing to grain growth at elevated temperature would induce fatal invalidity. The NC SiCp/AZ91 composite was isothermally annealed. A study on the thermal stability, including phase transformation, grain growth, softening, and strengthening mechanisms was carried out. After annealing treatment at 673 K for 240 min, the average grain size of AZ91-15vol.%SiCp composite increased from 29.0 nm to 53.1 nm. Coherent interface between nano-scale Mg17Al12precipitates and Mg matrix was certified by HRTEM. Pinning effect due to the dispersing submicron SiC particles with size of 164 nm and nano-scale Mg17Al12precipitates and dragging effect due to dissolving Al element were the reasons for excellent thermal stability. After annealing treatment, the hardness values of AZ91-xvol.%SiCp (x = 5, 10 and 15) composites were 1.61 GPa, 1.48 GPa and 1.78 GPa. Taking annealed AZ91-15vol.%SiCp composite as an example, there was no evident softening phenomenon and the decreasing ratio was ∼2% in comparison with milled composite with hardness of 1.82 GPa. Non-thermal sensitive SiC particles and high thermal stability Mg matrix played a key role in non-softening of composites.