Strengthening of electrically conductive Cu-Mn-Cr composite material with a copper-based metal matrix by nano- and micro-sized chromium particles

The article discusses the mechanisms of dispersion strengthening by nanosized chromium particles of a composite material with a copper-based metal matrix (Cu-MMNCr) without loss of electrical conductivity from which resistance welding electrodes are made. A study of the fractional composition of chromium nanopowder after grinding in a planetary-centrifugal mill was carried out and a method of introducing it into a copper melt using a tablet alloy was proposed. Uniform distribution of nanosized chromium particles in the melt is achieved by stirring by frequency modulation of current (in the range of 35-40 Hz from the operating frequency) in an alternating electromagnetic field. A thermodynamic analysis of the formation of reactions of interaction between melt components during the preparation of the Cu-MMNCr composite material was carried out. The wetting of nanosized chromium particles and lump chromium by copper melt was studied. A model of dispersion strengthening by nanosized chromium particles in structural changes of a composite material with a copper-based metal matrix, built on the fuzzy set hypothesis, is considered. The mechanical and electrical conductive properties of the Cu-MMNCr composite material were studied.