Effect of Ti Addition on the Microstructure and Mechanical Properties of SiC Matrix Composites Infiltrated by Al–Si (10 wt.%)–xTi Alloy

• Main Authors: Yajun Yu, An Du, Xue Zhao, Yongzhe Fan, Ruina Ma, Shijie Li, Wei Wang, Yaqi Cui, Xiaoming Cao
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Materials
• Subjects: infiltration; Ti addition; Ti₃Si(Al)C₂; bending strength; fracture toughness
• Online Access: https://www.mdpi.com/1996-1944/12/2/318

This paper proposes a simple reactive melt infiltration process to improve the mechanical properties of silicon carbide (SiC) ceramics. SiC matrix composites were infiltrated by Al⁻Si (10 wt.%)⁻xTi melts at 900 °C for 4 h. The effects of Ti addition on the microstructure and mechanical properties of the composites were investigated. The results showed that the three-point bending strength, fracture toughness (by single-edge notched beam test), and fracture toughness (by Vickers indentation method) of the SiC ceramics increased most by 34.3%, 48.5%, and 128.5%, respectively, following an infiltration with the Al⁻Si (10 wt.%)⁻Ti (15 wt.%) melt. A distinct white reaction layer mainly containing a Ti₃Si(Al)C₂ phase was formed on the surface of the composites infiltrated by Al alloys containing Ti. Ti⁻Al intermetallic compounds were scattered in the inner regions of the composites. With the increase in the Ti content (from 0 to 15 wt.%) in the Al alloy, the relative contents of Ti₃Si(Al)C₂ and Ti⁻Al intermetallic compounds increased. Compared with the fabricated composite infiltrated by an Al alloy without Ti, the fabricated composites infiltrated by Al alloys containing Ti showed improved overall mechanical properties owing to formation of higher relative content Ti₃Si(Al)C₂ phase and small amounts of Ti⁻Al intermetallic compounds.