交变磁场对7050铝合金凝固组织的影响

Effect of Alternating Magnetic Field on Solidification Microstructure of 7050 Aluminium Alloy

研究了在交变磁场作用下磁场频率变化对7050铝合金小型方坯静态成型铸坯熔体的弯液面、显微组织以及元素分布的影响。结果表明：当磁场频率为777Hz时弯液面较高；未施加磁场时铸坯的晶粒较粗，存在明显的粗大第二相，而施加磁场后铸坯的组织由细小、均匀的等轴晶构成，第二相基本呈网状分布；施加磁场后合金晶粒明显细化，晶粒尺寸由施加磁场前的171μm减小到121-128μm；施加磁场后，熔体内部金属元素都有部分烧损，当频率为777Hz时，镁、锌、铜三种元素分布比较均匀。

The effect of alternating magnetic field frequency on the meniscus, microstrncture and dement distribution of the static formed ingots of minitype square billet of 7050 alurninium alloy. The results indicate that the meniscus of melt was higher when the frequency of the alternating magnetic field was 777 Hz. The grains were coarse without the alternating magnetic field. There were obvious coarse second-phases in square billets. But the microstructure of square billets was composed of small and syrametrically equiaxed grains with the alternating magnetic field, and they distributed as reticulation. The grains were obviously refined from 171μm in the absence of the alternating magnetic field to 121-128μm in the presence of the alternating magnetic field. The dements of the alloy were partly burnt out. The distribution of Mg, Zn, Cu was relatively uniform when the frequency of the alternating magnetic field was 777 Hz.