Effect of Alloying on Dislocation Structure, Cracking and Fracture of Cu–Al and Cu–Mn Alloys in Low-Stability States

The influence of alloying on the local structural features of the experimental samples is studied in the regions of their potential cracking in the low-stability states with an aim of revealing the regularities of cracking and fracture. It is found out that the microcrack density in the neighborhood of the fracture region in the Cu+5at.%Al alloy, where cracking is prepared by the fragmented structure, is much higher than that in the Cu+6at.%Mn alloy, where cracking is prepared by the microbanded DSS. However, as we move from the site of potential fracture the microcrack densities in these microstructures become similar. It is shown that near the fracture region the dependence of the microcrack density on the fracture location is close to a parabolic curve, while at a larger distance the density values saturate and hardly change. The dependence of the average scalar dislocation density on distance is somewhat different: it is nearly linear. It is shown that the cellular and cellular-network DSSs represent material strengthening structures, which gives rise to an increase in the strain value at which cracking and subsequent fracture would occur.