交流磁场对Al-Fe合金凝固组织的影响

研究了交流磁场对Al-Fe合金中含铁相形态及分布的影响.近共晶Al-1.99%Fe(质量分数,下同)和亚共晶Al-0.90%Fe两种铝合金在3℃/min的冷却速率凝固过程中,施加强度为0.3 T,频率为20 Hz的交流磁场,并与未施加磁场的试样进行对比.实验结果表明,在这两种合金中,无论是先析出Al3Fe相还是先析出-αAl,施加交流磁场后,Al3Fe相均向试样的中心处富集.这是由于Al3Fe相的磁化率大于熔融铝基体的磁化率,使得Al3Fe相和铝基体相比受到指向样品轴线的更大的电磁力,从而导致其向试样中心处聚集.

Effect of Alternating Magnetic Field on Microstructure of Al-Fe Alloy

To investigate the effect of an alternating magnetic field on the morphology and distribution of iron-containing intermetallic phases in Al-Fe alloy, the near eutectic Al-1.99% Fe alloy and hypoeutectic Al-0.90% Fe alloy were solidified at a cooling rate of 3°C min in and not in the alternating magnetic field for comparison. The magnetic flux density at the center of the furnace and exciting frequency were 0.3 T and 20 Hz, respectively. The results showed that, whether Al3Fe or α-Al was precipitated first, Al3Fe phases were richened at the center of specimen when applying the alternating magnetic field to both Al-Fe alloys. This phenomenon can be explained the way the susceptibility of Al3Fe phase is higher than that of molten Al matrix, i.e., the electromagnetic force acting on Al3Fe phase is greater than that on Al matrix, thus causing the Al3Fe phase to aggregate at the center of specimen.