Study on the Medium-Frequency Magnetic Pulse Treatment of Fe52Co34Hf7B6Cu1 Amorphous Alloy by Positron Annihilation Technique

Abstract

The amorphous alloy specimens Fe52Co34Hf7B6Cu1 were treated by medium-frequency magnetic pulse. The treatment conditions were as follows: the pulsing magnetic field frequency and the acting time were kept at 1500 Hz, 10min, and the field intensity were 200Oe, 250Oe and 300Oe respectively. The structural defects change of specimens after magnetic-pulsing were researched by positron annihilation lifetime technique (PAS). The results show that in the as-quenched amorphous alloy, the positron are mainly localized at vacancy-sized free volumes in the amorphous based phase, and the amorphous alloy produced irreversible structural relaxation after being treated by the medium-frequency magnetic pulse which leaded to the decline of the annihilation lifetime τ1. With the increase of pulsing magnetic field intensity, new trapping centers of positrons are produced owing to the crystallization of amorphous phase, that leads to the intensity I2 increases and I1 decreases drastically. The soft magnetic properties of specimens treated by magnetic-pulsing were tested by vibrating sample magnetometer (VSM). The results show that the medium-frequency magnetic pulse (1500Hz, 200Oe, 10min) can improve the soft magnetic properties of Fe52Co34Hf7B6Cu1 amorphous alloy.