Study on microstructure of NiAl matrix high temperature lubricating composites containing BaO/TiO2 metallic oxide

Abstract

The microstructure of NiAl matrix high temperature lubricating composites containing BaO/TiO2 metallic oxides were investigated. The NiAl-BaO/TiO2 composites were fabricated by vacuum hot-pressing sintering. The diffraction peaks of NiAl slightly shifted to the left with the addition of BaO/TiO2 metallic oxide. The crystal plane distance of NiAl phase in the composite was bigger than that in NiAl material according to the Bragg equation. Meanwhile, the lattice distortion and dislocation occurred in the composite structure, which is probably due to the Ti element dissolve in the NiAl matrix during sintering. The cohesive energy and formation enthalpy of NiAl were improved with the incremental of Ti solution contents through density functional theory calculations, which was indicated that the Ti element could dissolve in the NiAl and was in good accordance with the results of XRD and TEM.