Zhang Rong, Zou Chunming, Wei Zunjie, Wang Hongwei, Liu Chuang
School of Materials Science and Engineering, Fujian University of Technology, Fuzhou 350118, China.
School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China.
Materials (Basel). 2023 Jun 9;16(12):4283. doi: 10.3390/ma16124283.
The formation of coarse primary Si is the main scientific challenge faced in the preparation of high-Si Al matrix composites. The SiC/Al-50Si composites are prepared by high pressure solidification, which allows the primary Si to form a SiC-Si spherical microstructure with SiC, while the solubility of Si in Al is increased by high pressure to reduce the proportion of primary Si, thus enhancing the strength of the composites. The results show that the high melt viscosity under high pressure makes the SiC particles almost "fixed" in situ. The SEM analysis shows that the presence of SiC in the growth front of the primary Si will hinder its continued growth and eventually form SiC-Si spherical microstructure. Through aging treatment, a large number of dispersed nanoscale Si phases are precipitated in the α-Al supersaturated solid solution. The TEM analysis shows that a semi-coherent interface is formed between the α-Al matrix and the nanoscale Si precipitates. The three-point bending tests shows that the bending strength of the aged SiC/Al-50Si composites prepared at 3 GPa is 387.6 MPa, which is 18.6% higher than that of the unaged composites.
粗大初生硅的形成是制备高硅铝基复合材料面临的主要科学挑战。采用高压凝固法制备SiC/Al-50Si复合材料，该方法使初生硅与SiC形成SiC-Si球形微观结构，同时高压提高了Si在Al中的溶解度，降低了初生硅的比例，从而提高了复合材料的强度。结果表明，高压下熔体粘度较高，使SiC颗粒几乎原位“固定”。扫描电子显微镜（SEM）分析表明，初生硅生长前沿SiC的存在会阻碍其继续生长，最终形成SiC-Si球形微观结构。通过时效处理，在α-Al过饱和固溶体中析出大量弥散分布的纳米级Si相。透射电子显微镜（TEM）分析表明，α-Al基体与纳米级Si析出相之间形成了半共格界面。三点弯曲试验表明，在3 GPa下制备的时效SiC/Al-50Si复合材料的弯曲强度为387.6 MPa，比未时效复合材料高18.6%。
