Effect of C/Mo Duplex-coating on Thermal Residual Stresses in SiC_f/Ti₂AlNb Composites

Abstract

Three-dimensional finite element physical models considering the layered distribution of materials at the interface were developed to study the effect of the coating system on distributions of thermal residual stresses in SiC_f/Ti₂AlNb composites. Two coating systems were comparatively studied, namely C coating and C/Mo duplex-coating. The thermal residual stresses after 1 080 °C/1 h solution treatment and 800 °C/20 h ageing treatment in the composites were also analyzed. The experimental results show that Mo coating can decrease thermal residual stress magnitude in the matrix. However, it would increase the thermal residual stresses in the interfacial reaction layer of TiC. The change of radial thermal residual stress in TiC layer is inconspicuous after solid solution and ageing treatment, but the hoop and axial thermal residual stresses increase obviously. However, the heat treatment can obviously reduce hoop and axial thermal residual stresses of the matrix, which is benefit to restrain the initiation and propagation of cracks in the matrix.

Keywords

finite element simulation / titanium matrix composite / SiC fiber / thermal residual stress