Features of structure formation and properties of cast titanium bronzes obtained using thermally synthesized powder ligatures

The paper presents the results of a study of the possibility of using powder metallurgy methods in obtaining cast titanium bronzes by using titanium-copper alloys obtained by thermal synthesis from a mixture of titanium hydride and copper powders as an alloying component. The conducted studies allowed optimizing the parameters for obtaining titanium intermetallics of the Ti-Cu and Ti-Cu-Al systems using metal powders as the starting material, and experiments were conducted on melting titanium bronzes using the developed powder alloys. Experimental melting of titanium bronze ingots was carried out for three bronze compositions: Cu - 2.7% Ti; Cu - 2.7% Ti - 0.5% Al and Cu - 2.7% Ti % - 1.0 % Al. As the results of the research showed, alloying of the copper melt with powder alloys made it possible to obtain cast alloys, the structure of which consists of a copper matrix phase with evenly distributed inclusions of copper-titanium intermetallic grains with a size of 2-8 microns. Experiments on smelting titanium bronze ingots also showed that the use of synthesized powder alloys significantly accelerates the smelting process, eliminates the need to use high temperatures required for dissolving pure titanium, and thereby reduces the burnout of alloying components, which allows for more accurate adherence to the specified chemical composition of the bronze. The study of the influence of heat treatment modes on the structure and physical and mechanical properties of cast titanium bronzes showed that after quenching of castings from 800 °С, the structure of cast alloys has a significantly dendritic character and noticeably lower hardness compared to the cast state. A significant increase in the level of hardness and strength of alloys is achieved by aging at 400 °С. The highest level of hardness and strength is noted for the Cu - 2.7% Ti alloy without aluminum. The dependence of the electrical conductivity of bronze, additionally alloyed with 0.5% Al and 3.0 % (wt.) Ni, on the titanium content is extreme: the maximum conductivity (~33 % IACS) is observed for the alloy with 1.5% (wt.) Ti.