Effects of untreated

magnetic field treatment

compound treatment of magnetic field and modifier on morphology and distribution of primary Mg

2

Si phase in 20 Mg2Si/Al composites were investigated.Effects of different voltage and frequency of magnetic field on primary Mg

2

Si phase with compound treatment were also described.The results reveal that the size of Mg

2

Si phase is decreased with magnetic field treatment or compound treatment

and the volume fraction of Mg

2

Si phase is increased gradually from the center to the edge of samples

showing gradient distribution

however the gradient distribution effect of Mg

2

Si phase is decreased after compound treatment.When the voltage is in the range of 0～300 Vor the frequency is in the range of 1～10 Hz

with the increase of the voltage or frequency

the size of Mg

2

Si phase is increased at first and then decreased

where the turning points are 200 Vand 5 Hz

respectively

and the gradient distribution effect is decreased gradually.The variation of wear resistance and hardness of the specimens is basically consistent with the volume fraction of Mg

2

Si phase.