Raman investigation of chemical reaction product in thermal‐treated SiCf/C/Mo/Ti6Al4V composite

Abstract

SiC fiber‐reinforced titanium matrix composite (TMC) is an interesting material for aerospace industry because of its excellent properties. Characterization of their interfacial reaction product is principal to further optimization of the TMCs. Here we report application of Raman spectroscopy to identify reaction products and their microstructural details in thermal‐treated SiCf/C/Mo/Ti6Al4V composite. Meanwhile TEM is performed to help explain phenomena in Raman result. Raman line scanning along interface indicates thickness of two sublayers (Ti5Si3(Cx) layer next to SiC fiber and TiCx layer next to matrix). The main Raman result of phase distribution is confirmed by TEM. While a 300‐nm Ti3SiC2 layer whose Raman features are similar with nearby Ti5Si3(Cx) layer is also detected. Raman peakshift in Ti5Si3(Cx) layer possibly results from residual stress or/and microstructural evolution caused by carbon solution. No evidence indicates Mo participation of interfacial reactions. However, Mo diffusion changes phase distribution of matrix alloy and affects interfacial reaction indirectly. Meanwhile, TEM and Raman results indicate that particles are TiCx and defective Ti3AlC2. Raman features of Ti3AlC2 particles differ from that of bulk material, which is attributed to defects. Although Ti3AlC2 formation mechanism is ambiguous, it possibly relates to TiCx formation nearby. Copyright © 2014 John Wiley & Sons, Ltd.