旋转磁场及快速凝固对Pb-Bi合金凝固组织的影响

摘要

The influences of rotating magnetic fields at different rotating speed on solidification microstructure of Pb-Bi alloys were studied. In Pb-52% Bi hypoeutectic alloy, rotating magnetic field can break the dendrite and re- fine grain. In Pb-66% Bi hypereutectic alloy, gravity segregation is completely eliminated. Besides, the samples of Pb-52% Bi hypoeutectic and Pb-60.9% Bi hypereutectic alloys were under-cooled up to 47 K and 66 K respectively by using silicone oil as denucleating agent and water cooling. In Pb-52% Bi hypoeutectic alloy, the refinement phe- nomenon occurs to e dendrite. In Pb-60.9% Bi hypereutectic alloy, the organization does not appear primary Bi phase with only the fine eutectic structure. For Pb-52% Bi hypoeutectic alloy in rapid solidification and rotating magnetic field, undercooling degree increases by 47 K to 55 K, and e sphares dispersedly distribute as droplets.%研究了不同转速的旋转磁场对Pb-Bi合金凝固组织的影响,对于Pb-52%Bi亚共晶,旋转磁场能碎断枝晶,细化晶粒;对于Pb-66%Bi过共晶,旋转磁场能消除比重偏析。另外,采用硅油净化法结合水淬使Pb-52%Bi亚共晶和Pb-60.9%Bi过共晶分别获得了47 K和66 K的较大过冷度,对于Pb-52%Bi亚共晶,金属间化合物ε相枝晶细化显著;对于Pb-60.9%Bi过共晶,组织中没出现初生相Bi,只有细密的共晶组织。对于Pb-52%Bi亚共晶在快速凝固的同时加旋转磁场,过冷度由47 K增大为55 K,ε相呈细小颗粒弥散分布。