Microstructure and mechanical properties of in situ produced Ti5Si3/TiC nanocomposites

The microstructure and mechanical properties of in situ produced Ti5Si3/TiC nanocomposites have been studied. Ti5Si3/TiC composites have been prepared by reaction hot pressing mixed powders of elemental Ti, Si and SiC. XRD, SEM, TEM were employed to characterize the structure of the composites. When no elemental Si is added, the resulting composite contains 65 vol.% Ti5Si3, with a small amount of carbon dissolved in it. The majority of the TiC particles are nanosized. A small fraction Ti3SiC2 grains, with an average size 100 nm, are located in the TiC particles while other elongated Ti3SiC2 grains in the Ti5Si3 matrix. The highest bending strength of the Ti5Si3/TiC composites is 510 MPa at room temperature, which is approximately 6 times that of the monolithic Ti5Si3 material. The fracture toughness of the composites exceeds that of pure Ti5Si3, and at 1100°C, the yield strength of Ti5Si3/35TiC reaches 800 MPa.