Estimation of distribution uniformity of Ti2NbAl particles in an aluminum-matrix composite material

Abstract

There was analyzed the distribution uniformity of reinforcing particles Ti2NbAl in composite materials (CM) based on aluminum alloy AO20-1, made by mechanical mixing. Samples with different structure dispersion were obtained by crystallization of a composite melt in molds made of materials with different thermal conductivity. There were used methods of digitizing the structure microphoto and mathematical statistics to estimation structural heterogeneity. Based on the results of processing the photographic images, there were constructed histograms of the frequencies of the distribution of intermetallic particles in the matrix. It is revealed that matrix structure refinement has positive effect on uniformity of the distribution. A significant decrease in the coefficient of variation for specimens with a finer structure also indicates a more uniform distribution of the reinforcing phase in this specimens. There was compared a wear resistance of the material and the uniformity of distribution of the Ti2NbAl powder in the matrix. A wear rate of composite materials was determined by testing on CETR UMT Multi-Specimen Test System under dry sliding friction conditions with sequential stepwise axial loading to values of 0.5, 1, 1.5, 2, 2.5, 3 MPa, at constant sliding speed of 0.5 m/s. The test time for each axial load was 2000 s, the friction path was 6000 m. It was observed a significant reduction in weight loss during friction for all CM samples as compared to the matrix alloy. The wear rate of CM specimens with a better distribution of the reinforcing component is reduced by more than 2.7 times as compared to specimens from the AO20-1 alloy, and with a less uniform distribution by 2.2 times