Diversity of Different-Scale Atomic Groups in a Cu–NbTi Composite under the Influence of Batch Hydroextrusion

Abstract

Using X-ray diffraction analysis, the patterns of changes in the atomic structure of Cu–NbTi composite materials were studied at P = 50 atm, a movable die rotation speed of 0.5 rpm, and the number of revolutions n = (0–5) rpm as a result of the action of batch hydroextrusion on the samples. It was found that the samples contain different-scale structural formations with long-range, mesoscopic, and short-range atomic orders. It was shown that the nonmonotonic change in atomic order with an increase in the rotation speed of the movable die is due to the order–disorder structural phase transition into a state with the formation of different-scale atomic groups with long-range, mesoscopic, and short-range atomic orders, in which the manifestation of new interatomic interaction forces characterizing the formation of intermetallic clusters of atomic groups is revealed. It was demonstrated that already in the initial state after compacting the samples, the presence of clusters in the copper matrix phase containing niobium and titanium is observed, which characterizes an increase in heterophase in the sample system under study. The result is a homogeneous, finely dispersed material containing uniformly distributed multiscale fractions of metallic and intermetallic phases in the form of crystalline, mesoscopic, and amorphous fractions. This structure exhibits increased strength, which is noticeable in the form of an increase in microhardness from 1.56 to 4.15 GPa.