Functionally oriented high-temperature composite materials

Abstract

The authors developed technology for obtaining surface composite materials. This technology includes high-energy mechanical treatment, high-velocity oxygen fuel spraying in a protective atmosphere and subsequent thermomechanical and thermal treatment of ZrCuNiCoTi and cBNNi3AlSiCCoY layers in a protective atmosphere. The processing allowed increasing the adhesive strength of the surface composites, reducing their porosity and improving their functional and operational properties. Staged methods of heat treatment and plastic deformation of surface layers have been developed. These methods stabilize the material structure while reducing residual stresses. On the basis of complex X-ray diffraction and electron microscopic studies, the structural parameters of surface composites were determined. It was shown that the ZrCuNiCoTi alloy is in the austenitic–martensitic state and has a nanocrystalline structure with a grain size of 80–120 nm. Meanwhile, the cBNNi3AlSiCCoY alloy consists of many intermetallic phases and inclusions and has a nanosized structure with a grain size of 100–200 nm. A microhardness study of the surface layers in ZrCuNiCoTi–cBNNi3AlSiCCoY composite showed that thermomechanical treatment increases microhardness. The experimental data were statistically processed. As a result, empirical mathematical dependences of the stress amplitude on cyclic durability were compiled. Mechanical tests included tests of NiCoTiZrHf–cBNCoMo, ZrCuNiCoTi–cBNNi3AlSiCCoY and TiNiZrHfCoCu–cBNCoNiAlY composites for multi-cycle fatigue during bending with rotation.