摘要
纯铝定向凝固过程加以高密度脉冲电流处理,研究了脉冲峰值电流密度对定向凝固组织的影响。随着脉冲电流密度的增大,定向凝固组织经历了由柱状晶→胞状晶→发达的枝晶→柱状晶3个演化阶段。基于感应磁场与脉冲电流的耦合作用,从电磁流体力学方面分析了高密度脉冲电流对凝固组织形成的作用机制。高密度脉冲电流在金属熔体内感生高频振荡磁场,并感生动态径向电磁压力,影响凝固界面上方金属液流场分布与金属凝固前沿的温度梯度,并对枝晶臂有冲刷作用,从而改变凝固组织形态。
Effects of pulsed peak value current on directional solidification structure in the pure aluminum were investigated by employing high intensity pulsed current during directional solidification process.It is found that with increasing in high intensity pulsed current,the directional solidification structure in the pure aluminum is evolved from regular columnar crystal to cellular crystal and then to developed dendrite and finally to columnar crystal.Taking into account of coupling effects of inductive magnetic field and pulsed current,based on electromagnetic hydromechanics,role mechanism of high intensity pulsed current on solidification structure was analyzed.The evolution of solidification structure is attributed to high-frequency oscillatory magnetic filed induced by high intensity pulsed current causing dynamic radial electromagnetic pressure which can affect distribution of the flow field and temperature gradient on the front face of liquid metal above solidification interface and scour the dendritic arm.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2010年第5期450-452,共3页
Special Casting & Nonferrous Alloys
基金
国家自然科学基金资助项目(50874093)
关键词
脉冲电流
定向凝固
枝晶间距
感生电磁力
电磁流体力学
Pulsed Current,Directional Solidification,Dendritic Arm Space,Induced Electromagnetic Pressure,Electromagnetic Hydromechanics
