Estimating the Uniformity of the Distribution of Ti2NbAl Particles in an Aluminum-Matrix Composite Material

摘要

Abstract The uniformity of the distribution of Ti2NbAl reinforcing particles in composite materials (CMs) based on an AO20-1 aluminum alloy fabricated by mechanical stirring was analyzed. Samples differing in the structure dispersion were obtained by solidification of a composite melt in molds made of materials with different thermal conductivities. To estimate the structural heterogeneity, the techniques of digitizing the photographic images of the structure and mathematical statistics were used. On the basis of these results, histograms of the distribution of intermetallic particles in the matrix were constructed. It was found that the refinement of the matrix structure positively affects the uniformity of the distribution of intermetallic particles. A significant decrease in the coefficient of variation for samples with a finer structure of the matrix also indicates a more uniform distribution of the reinforcing phase in these samples. The correlation between the wear resistance of the material and the uniformity of the distribution of the Ti2NbAl powder in the matrix was studied. The wear intensity of CMs was determined by testing under dry sliding friction conditions during successive stepwise axial loading to values of 0.5, 1, 1.5, 2, 2.5, and 3 MPa at a constant sliding speed of 0.5 m/s. The test time was 2000 s at each axial load and the friction path length was 6000 m. A significant reduction in mass loss during friction was observed for all CM samples as compared to the matrix alloy. The wear intensity of the CM samples with a more uniform distribution of the reinforcing component is reduced by more than 2.7?times, and with a less uniform distribution, it is reduced by 2.2 times as compared to the AO20-1 samples.