脉冲电流对形核率影响机制的研究

Research of Effects on Mechanism of Nucleation Rate by Pulse Current

根据经典的形核理论及脉冲电流对凝固组织的作用机理,从电磁场理论出发研究了脉冲电流作用下晶粒细化的作用机制。通过讨论过冷度的变化对形核率的影响,研究了电流产生的电磁力效应及焦耳热效应对过冷度的影响,建立了电流与过冷度的关系式。研究结果表明了电流对形核率的影响主要是由于电流改变了过冷度,电流能否细化凝固组织由电磁力和焦耳热效应引起的过冷度的变化决定,并与脉冲宽度有关。

According to classical solidification theory and the mechanism of solidification microstructure under pulse current, the effect of super-cooling degree variation on nucleation rate was discussed. The influence of electromagnetic stress effect and Joule heat effect on super cooling degree were researched. The relationship between current and super-cooling degree was set up. It expatiated the effect of pulse current on nucleation rate was because of super-cooling degree variation by pulse current. The pulse current influenced solidification structure, which was not determined by the effect of electromagnetic stress effect and Joule heat effect on super-cooling degree variation. Electromagnetic stress effect, Joule heat effect on super cooling degree and their variations can cause the electric current to fine solidication, moreover, which related with pulse width.