The influence of aging on microhardness and electrical conductivity of Cu–2 wt. % Be alloy

Abstract

Goods made of beryllium bronzes got widespread use in the industry due to the complex of properties: high heat conductivity, strength, hardness, wear resistance, and corrosion resistance. They are not magnesium-based and do not spark on impact; therefore, they are essential for the production of non-sparking tools. The alloys of this system are used in the electrical engineering industry; consequently, it is necessary to pay attention to the improvement of the material’s electrical conductivity. The paper studies the microstructure, microhardness, and electrical conductivity of the Cu–2 wt.% Be alloy exposed to high-pressure torsion (HPT). The authors investigated the microstructure and fine structure of the alloy in various states. The study showed that HPT leads to the formation of an ultrafine-grained nanostructured (UFG NS) state with an average size of grains/subgrains of 22±1 mmn. Additional ageing of samples after HPD led to a slight increase in the grains/subgrains size up to 31±1 mmn. In both states, the authors observed nanosized deformation twins. The authors studied the dependences of microhardness and electrical conductivity of the alloy after HPD on the time of further ageing. The study identified that the microhardness increases from 122±3 HV in the initial state up to 525±8 HV after HPD and ageing. The investigation shows that the electrical conductivity substantially better recovers after ageing of the UFG NS state compared to the initial state. The electrical conductivity of the UFG NS state increased from 14.5±0.1 % IACS up to 27.5±0.6 % IACS in conditions similar to the initial state ageing. Therefore, resulting from such processing, the Cu–2 wt.% Be alloy is characterized by its advanced strength properties and electrical conductivity.