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采用单辊实验技术研究了Co-Sn二元合金的急冷快速凝固行为,并通过将金属熔体热传导方程和Navier-Stokes方程相耦合,理论计算了液态合金的冷却速率.实验发现,Co-20%Sn亚共晶合金的初生aCo相的生长形态对冷速变化十分敏感,低冷速下在合金条带中部会形成一定厚度的柱状aCo枝晶区.随着冷速的增大,柱状晶区减小并逐渐趋于消失,凝固组织以均匀细小的aCo等轴晶和分布于其间的gCo3Sn相为特征.Co-34.2%Sn共晶合金形成了全部的不规则共晶组织.随着冷速的增大,一方面两种合金组织明显细化,均匀性显著提高;另一方面晶体缺陷数量增多,对自由电子的散射作用增强,从而导致电阻率的显著增大.晶界散射系数r→1,可使用M-S模型对快速凝固Co-Sn合金的电导特性进行理论计算.
Single-roll experimental technique was used to study the rapid solidification behavior of Co-Sn binary alloy. The cooling rate of liquid alloy was theoretically calculated by coupling the heat conduction equation of metal melt with the Navier-Stokes equation. It was found that Co-20 The growth morphology of the primary aCo phase of the% Sn hypoeutectic alloy is very sensitive to the change of the cooling rate, and a columnar aCo dendritic zone with a certain thickness is formed in the middle of the alloy strip at a low cooling rate. As the cooling rate increases, The region of the Co-34.2% Sn eutectic alloy formed all of the irregular eutectic structure, and with the decrease of the region and gradually disappear, the solidified microstructure was characterized by uniform and fine aCo equiaxed grains and gCo3Sn phase distributed between them On the other hand, the number of crystal defects increases and the scattering effect of free electrons increases, resulting in a significant increase of the resistivity. The grain boundary scattering coefficient r → 1, the conductivity model of the rapidly solidified Co-Sn alloy can be theoretically calculated using the MS model.