The structure of castings of cast composites of the Cu-V system obtained by electron beam casting

Abstract

Cu-V alloys are promising composite materials for electrical engineering application. They have higher normal and high-temperature strength with minimal loss of electrical conductivity, caused by alloying. The production of such alloys is a complex technological task due to the insolubility of vanadium in copper, its refractoriness and high reactivity. Most of the technologies that make it possible to obtain a uniform distribution of small vanadium inclusions in the copper matrix are complex, multi-stage and expensive. They involve using a powder metallurgy and some other complex methods. The cheapest way to produce ingots and products from a Cu-V alloys is the use of foundry technologies. Due to the insolubility of vanadium in copper and its lower density, the electron beam casting technology was chosen to produce such castings. It provides concentrated spot heating of metal in a vacuum and implements electromagnetic stirring of the melt. It makes it possible to obtain a homogeneous superheated melt and pour it in a vacuum. At the same time, it is important to accelerate the crystallization of the casting as much as possible to ensure the minimum size and uniform distribution of vanadium particles and prevent them from floating. So, this work is devoted to determining the technological features of obtaining high-quality cast composites based on Cu-V system with different chemical composition under the conditions of the specified technology. When producing alloys with a vanadium content of up to 2 % wt., heterogeneity of dispersed particles distribution is then greater, then higher concentration of vanadium is. It is shown that its optimal content in copper corresponds to a concentration of 0,2 % wt., which is close to peritectic. For such an alloy in the cast state, the insoluble strengthening particles of vanadium are uniformly distributed and have dimensions of about 0.5-1 μm. It is important that when remelting such alloys by the common method of induction melting, it is possible to ensure the uniform distribution of vanadium and to preserve the small size of its particles.