Modification of copper alloys with ultrafine powders

Abstract

Modification of metal melts by mechanochemically activated ultrafine powders (UDP) makes it possible to obtain ferrous and non-ferrous metal alloys with fundamentally new performance properties due to changes in the structure of metal alloys. The purposes of this work were to analyse the efficiency of the process of modifying copper alloys with ultrafine powders and to develop a special device for introducing a modifier into the melt. Experimental studies of the process of modifying melts of aluminum, silicon and tin bronze with mechanochemically activated UDP of natural graphite, as well as silicon and aluminum oxides with a fraction of -100+0 microns in a concentration of 0.2-0.25 % were carried out. It is shown that the modification of bronze melts by the above-mentioned powders affects the microstructure of alloys, intensively grinding it in comparison with the initial structure. It was found that the reduction in the size of the dendritic cell in comparison with the initial alloy reaches 25%, and the micrograin - 230%. Grain grinding leads to an increase in the mechanical properties of copper alloys, such as Brinell hardness HB, tensile strength σb, elongation δ. For more efficient implementation of the process of modifying metal melts with ultrafine powders, an original design of a device for introducing modifiers into the melt has been developed, characterized by simplicity and cost-effectiveness of execution.

Keywords

• copper bronzes
• ultrafine powders
• udp
• mechanical properties
• modification
• structure