Specific features of grain structure evolution in HPT-nanostructured Cu-7.4Sn bronze during subsequent heating, obtained by statistical analysis

Abstract

Listen

Translate article

The use of the statistical analysis approach based on the application of finite mixture models and using an expectation-maximization algorithm to describe the experimental grain size distributions of HPT-nanostructured Cu-7.4Sn bronze allows us to decompose them into a set of groups of grains with sufficient accuracy. It is shown that the saturation stage after one revolution of HPT has not been reached in comparison with the sample after five revolutions. At the same time, grain structure evolution during heating depends on the initial strain state. However, the character of the evolution of both samples is similar. It is demonstrated that grains which form one of the groups are characterized by higher density of defects and enhanced energy; this decreases the volume fraction of the group during heating, with hardly changing other features. The other groups of grains seem to be formed under the influence of relaxation processes during subsequent annealing. Moreover, each subsequently formed group of grains demonstrates more intensive growth during heating, while the volume fraction of existing groups slows down until they disappear completely.