The effects of different magnetic field excitation currents on the solidification microstructure and mechanical properties of ZL205A alloy were investigated by using downward traveling wave magnetic field

and the evolution law ofθphase was analyzed.The results show that the traveling wave magnetic field can refine the alloy structure to form fine near-equiaxed crystal structure

and improve the tensile strength and elongation of ZL205A alloy.Meanwhile

the excitation current of the magnetic field has a direct effect on the refinement effect of solidification structure.With the current frequency of 50 Hz

the desirable excitation current for ZL205A alloy is in range of 10～20 A.In addition

with the increase of the excitation current

theθphase appears to be paramagnetic in the magnetic field.As the magnetic field increase

the nucleation undercooling degree is increased

so the nucleation rate is increased andθphase is broken down.When the excitation current is less than 10 A

the electromagnetic force generated by the magnetic field has a great influence on the size of theθphase.When the magnetic current is 20 A

the melt viscosity is increased as a result of the magnetic field Lorentz force

which can prevent theθphase from further refinement.