Study on the microstructure and properties of a phosphor copper ball during its formation process

Abstract

Abstract Microcrystalline phosphor copper balls with a diameter of 28 mm were prepared via continuous extrusion upsetting. Optical microscopy and electron backscatter diffraction were used to study the microstructural evolution of phosphor copper balls during the formation process. In addition, the hardness distribution and tensile properties were tested. The results show that fine dynamic recrystallisation grains and twins were formed after continuous extrusion and that the grains were further refined after upsetting. After continuous extrusion upsetting, there were typical 〈111〉, 〈100〉, and 〈110〉 fibre textures, and the proportions of these three textures in the individual samples were different. The change in microhardness was affected by the microstructure. The increase in the hardness value from casting and continuous extrusion upsetting was owing to pronounced grain refinement. The grain sizes from the centre to the edge were similar, and the grain refinement was more uniform. Notably, the grain size of the extruded rod was still fairly uniform from the centre to the edge in the radial direction. It can be concluded that the continuous extrusion-upsetting phosphor copper anode is more conducive to the formation of black film, that is, it is more suitable for electroplating anode material.