Microstructure uniformity control of CuCr alloy prepared in-situ by aluminothermic reduction coupled with permanent magnetic stirring

Abstract

CuCr alloy with Cr contents of 50 wt% was synthesized in-situ by aluminothermic reduction under magnetic/temperature coupling, and the uniformity of the microstructure and its regulation were studied. The effect of different slagging coefficients on the composition and microstructure uniformity of the alloy was investigated. The microstructural evolution of the alloy and the effects of heat treatment on the microstructure and properties (conductivity and hardness) of as-cast CuCr50 alloys were researched. The results showed that when n(CaO/Al2O3)= 0.2, the microstructure of the alloy is uniform, the Cr-rich phase solidifies rapidly under the coupling field, and the grains can be refined to 25 µm. The supersaturated solid solution with a Cr solution of 2.44 % is produced in the matrix. After heat treatment, the Cr particles are refined to 20 µm and the microstructure tends to exhibit uniform growth. The supersaturated phase was precipitated, and the solid solubility of Cr is reduced to 1.27 %. The hardness increased by 15.43 % (87.5 HB to 101 HB) and the electrical conductivity increased by 1.46 times (13.82 MS/m to 20.03 MS/m). This method is expected to provide an effective method for the preparation of Cu-based immiscible alloys.