Influence of small amounts of Fe and V on the synthesis and stability of Ti3SiC2

Polycrystalline bulk samples of (Ti1-yMey)3SiC2, where Me=Fe or V and y=0.01 to 0.1, were fabricated by reactive hot isostatic pressing of a mixture of Ti, C (graphite), SiC and Fe or V at 1450°C for 4 h under a pressure of 60 MPa. X-ray diffraction and scanning electron microscopy of the fully dense samples have shown that small amounts of Fe and V interfere with the reaction between Ti, C and SiC leading to the presence of SiC, TiCx, as well as different Fe and V-containing phases in the final microstructures. The presence of these impurity phases also reduces the temperature at which Ti3SiC2 decomposes. The decomposition is manifested by the formation of a network of pores when the samples are annealed at 1600°C, a temperature at which pure Ti3SiC2 is thermally stable. The concentration threshold for this decomposition is as low as 1 at%.