Effects of SiC nanowires and whiskers on high-entropy carbide-based composites sintered at low and high temperatures

This study aimed to investigate the toughening effects of SiC nanowires (SiCnw) and SiC whiskers (SiCw) on high-entropy carbide based composites prepared at different temperatures (1600 degrees C and 2000 degrees C). At low temperature (1600 degrees C), SiCnw and SiCw maintain their original morphology and properties, and exhibit the good toughening effects. The SiCnw with larger aspect ratio and more curly wires exhibit a much stronger toughening effect on the (Ti0.2Zr0.2Nb0.2Ta0.2Mo0.2)C0.8 composites reinforced with 15 vol.% SiCnw, which shows the highest value of fracture toughness about 6.7 MPa center dot m1/2. However, at high sintering temperature (2000 degrees C), SiCnw and SiCw are prone to thermal-induced damages, which significantly reduces their mechanical properties, and thus, toughening effects on (Ti0.2Zr0.2Nb0.2Ta0.2Mo0.2)C0.8 composites. The addition of SiCw, which have better thermal stability at 2000 degrees C, results in the (Ti0.2Zr0.2Nb0.2Ta0.2Mo0.2)C0.8-15 vol.% SiCw composite exhibiting relatively better fracture toughness, about 3.7 MPa center dot m1/2. Based on the results of the current study, the critical influence of SiCnw and SiCw on the toughening of (Ti0.2Zr0.2Nb0.2Ta0.2Mo0.2)C0.8 composites is highly dependent on their high-temperature thermal stability.