Effect of C/Mo duplex coating on the interface and mechanical properties of SiCf/Ti6Al4V composites

SIC fiber (with C/Mo duplex coating) reinforced Ti6Al4V-matrix composites were fabricated by vacuum hot pressing. Tensile property of the as-prepared composites was tested at room temperature. In order to study the interfacial thermal stability of the composites, vacuum thermal exposure of the as-prepared composites was carried out at 700 degrees C and 800 degrees C for different duration. The interfacial microstructure of the as-prepared and thermally-exposed composites was investigated by means of scanning electron microscope and energy dispersive spectrometer. The results indicate that the interfacial phase sequence of the as-prepared composite is SiC vertical bar C/Mo vertical bar TiC vertical bar Mo-residual+ beta-Ti vertical bar beta-Ti+alpha-Ti-primary vertical bar Ti6Al4V from SiC side to the matrix. The interfacial microstructure has no obvious evolution when the composites were thermally exposed at 700 degrees C, which indicates an excellent thermal stability of C/Mo duplex coating. Furthermore, there still exists C/Mo duplex coating at the interface when the composites were thermally exposed at 800 degrees C for up to 100 h. Therefore, the C/Mo duplex coating exhibits a more outstanding thermal stability than a single Mo coating at elevated temperatures below 800 degrees C. The tensile strength of the as-prepared composites was a little higher than that of the composites with only C coating, which should attribute to the good effect of the C/Mo duplex coating. (c) 2013 Elsevier B.V. All rights reserved.