INFLUENCE OF DYNAMIC CHANNEL-ANGLE PRESSING ON RELATIVE ENERGY OF GRAIN BOUNDARIES IN HAFNIUM BRONZE

Abstract

The aim of the work is to evaluate the relative energy of grain boundaries of hafnium bronze deformed by dynamic channel-angle pressing (DCAP) using scanning tunneling microscopy. In the course of this work, the following studies were carried out. 1. The sample preparation technique of Cu-Hf samples subjected to severe plastic deformation (SPD) by DCUP for subsequent scanning tunneling microscopy studies was perfected, providing an averaged RMS surface roughness value of about 2 nm. 2. Scanning tunneling microscopy images of the hafnium bronze surface structure were obtained and processed using the Gwyddion application program. As a result, grain boundary profiles were calculated, on the basis of which the values of dihedral angles at the bottom of etching grooves were calculated and the relative energies of grain boundaries were calculated. 3. It was found that after deformation of DCUP, the average relative energy of grain boundaries is almost two times higher than the relative energy of grain boundaries of polycrystalline copper. Thus, nonequilibrium grain boundaries are formed in the samples as a result of DCUP. 4. It is shown that with the increase in the number of ACP passes there is an increase in the average relative energy of grain boundaries, which indicates an increase in the degree of their non-equilibrium.