In-situ synthesis of SiC particles by the structural evolution of TiC sub(x) in Al-Si melt

• Published in: Journal of alloys and compounds 2014-11, Vol.613, p.407-412
• Main Authors: Nie, Jinfeng, Li, Dakui, Wang, Enzhao, Liu, Xiangfa
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Aluminum base alloys; Evolution; Intermetallic compounds; Mechanical properties; Melts; Particulate composites; Silicon; Silicon carbide
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2014.06.040

A facile method has been developed to in-situ synthesize SiC particles utilizing the structural instability and evolution of TiC sub(x) in Al-Si melt. It is considered that the synthesis of SiC particles occurs via the gradual reaction between TiC sub(x) and Si atoms, whilst Si content plays the crucial role in this approach. If the Si content in the melt is above 30%, TiC sub(x) directly reacts with Si and Al to form SiC, but the needle-like TiAl sub(x)Si sub(y) phase formed simultaneously will do harm to the mechanical properties of the composites. Thus, it is proposed to add B element in the melt to transform the TiAl sub(x)Si sub(y) into TiB sub(2) particles. Therefore, the SiC and (SiC + TiB sub(2)) hybrid-particles reinforced Al-18Si composites were successfully prepared using the method. In the composites, the SiC particles have the size range from 2.5 to 7.5 mu m and a block-like morphology. Furthermore, the mechanical properties of base alloy, including the wear resistance and macro-hardness, have been obviously improved by the in-situ SiC particles. Besides, the relevant underlying mechanisms are also discussed.