Temperature-dependent evolution of interfacial zones in SiCf/C/Ti17 composites

Abstract

The continuous SiC fibre reinforced Ti matrix composites are usually subjected to elevated service temperature, representing a wide range of possible applications relying on the corresponding interfacial stability. SiC fibres coated by a turbostratic C reinforced Ti17 matrix composites (SiC_f/C/Ti17) were fabricated and the evolution of interfacial zones subsequently to processing of thermal exposure to distinct conditions: 450 °C/600 h, 800 °C/600 h and 1100 °C/2 h was investigated. The corresponding low-temperature long term and high-temperature short term applications were evaluated. It was discovered that the interfacial zone of the as-processed SiC_f/C/Ti17 could be described as turbostratic C||amorphous C||fine-grained TiC||transition TiC||coarse-grained TiC, remaining stable subsequently to 450 °C/600 h of exposure. The same thickness of each sub-layer was observed as the as-processed sample was identified. The 800 °C/600 h thermal treatment induced apparent increment in the coarse-grained TiC sub-layer thickness, reaching twice the as-processed sample increment as well as the grains growth in the fine-grained TiC sub-layer. On the contrast, the 1100 °C/2 h thermal treatment not only induced a remarkable increment in thickness of the coarse-grained TiC sub-layer, but also actuated the grain growth of the fine-grained TiC sub-layer. Consequently, it merged the sub-layer with the transition TiC sub-layer. The diffusion behavior of C atoms activated by different temperatures could be responsible for the aforementioned temperature-dependent evolution of the interfacial zones in the SiC_f/C/Ti17.