Determination of the coherence of the interface between the solid solution and intermetallic phasesin monocrystal cast alloys based on the Ni3Al intermetallic compound by the X-ray diffraction method

Abstract

The paper considers splitting of the solid solution gamma phase diffraction peaks in the nickel heat-resistant alloys, including alloys based on the Ni3Al intermetallic compound with the heterophase structure. It is shown that the effect of splitting the solid solution gamma phase diffraction peaks is missing in the alloys based on the Ni3Al intermetallic compound with heterophase structure, in contrast to the nickel heat-resistant alloys. It was established that splitting of the solid solution gamma phase diffraction peaks in the diffraction pattern was caused by tetragonal distortion of the gamma phase crystal lattice (solid solution) exposed to the interphase stresses. Only under condition of the interphase boundary coherence exposed to the interfacial stresses the tetragonal distortion of the gamma phase crystal lattice (solid solution) appeared. Therefore, a conclusion could be made based on the absence of splitting the gamma phase diffraction peaks that the interphase boundary (interface) coherence was missing in alloys based on the Ni3Al intermetallic compound with the heterophase structure.