Study of the Structure and Properties of Cermets Based on the NiAl–Al2O3 System

The powder metallurgy method, including the mechanical activation of powders in a planetary mill and spark plasma sintering at 1470°C in an inert atmosphere, is used to obtain NiAl–45 vol % Al 2 O 3 cermet samples with the addition of nanoparticles of magnesium aluminum spinel in an amount of 0.05 vol %. The features of their microstructure are investigated. Spinel nanoparticles are located at the boundaries between the grains of the composite components. The results of X-ray diffraction analysis at t = 25 and 800°C are obtained. The main components of the material at t = 20°C are α-Al 2 O 3 and NiAl. The dependence of internal friction on the temperature in the range of 20–900°C is studied, and the influence of magnesium aluminum spinel nanoparticles on the nature of its change is established. The internal friction curve shows that vibration damping occurs up to 600°C. Dependences of the bending strength of cermets at t = 20–750°C are determined. The positive effect of the introduction of a small amount of magnesium aluminum spinel on the elastic properties of composites is established. The best mechanical properties are demonstrated for NiAl–42 vol % Al 2 O 3 –0.05 vol % MgAl 2 O 4 samples. On average, the ultimate bending strength of this material is 8–15% higher compared to samples without nanoparticles. The materials obtained in this research had a bending strength under normal conditions of 460–490 MPa. A summarizing analysis of NiAl–Al 2 O 3 cermet research is carried out to determine the nature of the dependence of the bending strength on the ratio of components. It is found that it has an extreme nature: the maximum is observed when using the ratio of aluminum oxide to aluminum nickel equal to 0.5.