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

Polycrystalline bulk samples of(Ti1-yMey)(3)SiC2, where Me = Fe or V and y = 0.01 to 0.1, were fabricated by reactive hot isostatic pressing of a mixt ure of Ti, C (graphite), SIC and Fe or V at 1450 degrees C for 4 h under a pressure of 60 MPa. X-ray diffraction and scanning electron microscopy of t he 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, TiC x, as well as different Fe and V-containing phases in the final microstruct ures. 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 degrees C, a t emperature at which purl Ti3SiC2 is thermally stable. The concentration thr eshold for this decomposition is as low as 1 at%. (C) 2000 Elsevier Science Ltd. All rights reserved.