交变磁场下Cu-Fe复合材料的凝固组织与性能

Solidification microstructure and properties of Cu-14Fe composites under alternating magnetic field

研究了低频交变磁场下Cu-14Fe原位复合材料的凝固行为,讨论了磁场施加和磁场强度对铸锭组织、溶质分布和性能的影响。结果表明,Cu-14Fe复合材料常规凝固组织中Fe相主要呈枝晶和不规则长条状分布,施加交变磁场后,Fe相转化成梅花状或等轴状晶粒,分布更均匀。交变磁场的施加导致Cu基体中Fe溶质含量降低,磁场强度越大,浓度下降越明显。交变磁场的施加大幅降低了铸锭中的氧含量,提高了材料的电导率,降低了基体硬度。交变磁场对Cu-14Fe原位复合材料凝固过程的影响分别从动力学和热力学方面进行了分析,磁场一方面通过力场改变了熔体的热流和溶质分布,另一方面作为能量场作用于熔体影响了晶胚形核的势垒,从而影响了Cu-14Fe原位复合材料的凝固组织与性能。凝固过程中施加交变磁场有利于Cu-14Fe原位复合材料中Fe相的细化和析出。

The solidification behavior of Cu-14Fe in situ composites under alternating magnetic field （AMF） was studied. The effects of magnetic field and field intensity on microstructure, solute distribution and material performances of the composites were discussed. The results show that with AMF treatment, rod shape and larger size Fe dendrites are reduced, the dendrites change to the club shaped and equiaxed grains, and distribute uniformly. AMF has effect on the solute distribution in Cu matrix. The Fe content in Cu matrix has been reduced with AMF treatment, and the content decrease with strengthening of field intensity. The application of AMF causes the oxygen content of ingots decrease rapidly, and increases the eonductivities of materials. The matrix hardness value decreases with strengthening of field intensity. The effects of magnetic field during solidification process were discussed by thermodynamics and kinetics. For the magnetic field, on the one hand, force field has changed the melt flow and solute distribution; on the other hand, the potential barrier of nucleation has been affected as the energy field, thus affecting the solidification structure and performances of Cu-14Fe in situ composites. The application of AMF in solidification process of Cu-14Fe in situ composites has contributed to refine primary Fe dendrites and the precipitation of Fe from Cu matrix.