Effect of cooling rate on morphology and distribution of Fe phase in solidification structure of Cu-20Fe alloy

Abstract

Cu–Fe alloys are high-strength and high-conductivity copper-based materials with great potential. The solidified structures comprise of an Fe phase and Cu matrix, and the solidification structure significantly affects the properties of the alloys. The cooling rate during solidification affects the Fe phase morphologies, sizes, and distribution uniformity in Cu–Fe alloys, making it an essential control parameter. The solidification process of a Cu-20Fe alloy were analyzed at cooling rates from 0.3–13.0 °C/s using a confocal scanning laser microscope (CLSM). The secondary dendrite arm spacing (SDAS) and fractal dimension (D) were used to quantitatively characterize the solidification morphology. The uniformity (U) was used to describe the distribution uniformity of the Fe phase in the solidification structure. The results indicate that the morphology and distribution uniformity of the Fe phase were significantly affected by the cooling rate. The relationship between SDAS (λ2) and cooling rate (C) gave the expression: λ2 = 12.05 · C−0.39. The cooling rate during solidification changed the morphology of the dendrites and the overall solidification structure, likely because of the solute diffusion and temperature gradient in front of the solid–liquid interface being affected. In addition, the distribution uniformity of the Fe phase in the solidification structure significantly changed with the solidification time. There was a linear relationship between uniformity and SDAS: U = 82.50−1.03 × λ2. The morphology and distribution uniformity of the Fe phase in the solidification structure of Cu-Fe alloys can be controlled by adjusting the cooling conditions during solidification. This could allow for the enhancement of the functional properties of the alloy and possibly lead to further applications.