电磁搅拌法合成(Al_2O_3+Al_3Zr)p/A356复合材料的凝固组织

Solidification Microstructure of (Al_2O_3+Al_3Zr)p/A356 Composites Synthesized by Electromagnetic Stirring

在电磁搅拌作用下用A356-Zr(CO3)2组元通过熔体反应法原位合成了Al2O3、Al3Zr颗粒增强铝基复合材料,扫描电镜观察试样凝固组织发现:复合材料中内生增强颗粒粒度为1～3μm,并随着搅拌强度的增加,增强颗粒在基体中的体积分数和弥散度显著提高,原因是电磁搅拌促进了传热和传质扩散,改善了原位合成动力学条件;同时Si相形貌由片状初晶硅向针状、细棒状共晶Si转变,随搅拌强度的增加硅相变质,这是电磁搅拌和内生颗粒共同作用的结果.

(Al_2O_3+Al_3Zr)p/A356 composites were synthesized by melt-reaction in A356-Zr(CO_3) system with electromagnetic stirring.Observation of solidified microstructure by SEM show that the volume fraction and dispersity of reinforced particulate with the size of 1～3 μm in matrix can be improved with the stirring intensity increasing due to the electromagnetic stirring promoting heat transfer and solute diffusion to improve in-situ synthesized kinetics.Meanwhile,co-action of electromagnetic stirring and in-situ particulate results in the transformation of Si phase from sheet primary Si to needle-like or fine-rod eutectic Si.