Research Of Viscosities Of Metallic Melts Under Horizontal Magnetic Field

The viscosity of metallic melts is a kind of atomic motion among the melts.The viscosity reflects the fluidity of the metallic melts directly.And the viscosity shows the heat transfer and the mass transfer in the metallic melts.So,studying the viscosity of metallic melts can help understand the solidification behaviors of metallic melts and control metallic forming ability to obtain the metal of good quality.The viscosity of metallic melts can be used to reflect the change of liquid structure.So,according to the viscosity,we can learn the internal structural change of the metallic melts.The change rate of viscosity to the temperature is the fragility of metallic melts,and fragility can reflect the glass forming ability of metallic melts.So,the viscosity of metallic melts is an important parameter to predict the glass forming ability of metallic melts.Studying the viscosity is significantly important both for the basic research and the technological application.Gallium is a kind of semimetal,which possesses low melting point and good corrosion resistance.As a kind of semiconductor material,Gallium can be used widely,such as microwave communications,magnetic materials,solar cells,medicine and photovoltaic industry.In recent years,as a kind of new material,Gallium alloys has great application prospects in many fields.In present work,the effect of magnetic field on the dynamic viscosity of Ga-based melts was systematically studied using the torsional viscometer with the horizontal magnetic field.The theoretical model has been established to describe the relationship between the viscosity and magnetic intensity quantitatively.The effect of magnetic field on the glass forming ability of Ga-based metallic melts has been studied.And the structure of Ga-based metallic melts has been computed by molecular dynamic simulation to study the effect of magnetic field on the viscosity of metallic melts.The reason for the viscous change under the magnetic field has been explained from the point of micro-atomic view,which has laid the foundation for the theoretical research of metallic melts.The present research shows that with the increasing temperature,the viscosity of Sn₉₇Fe₃?Sn₉₄Fe₆?Sn₉₅Co₅?Sn₉₅Mn₅?Al₉₇Ni₃?AI₉₂Ni₈?Ga₉₈Fe₂ and Ga₉₈Cr₂ decreases,and the viscosity all accords with Arrhenius equation.With the increase of the magnetic field,the pre-exponential factor increases.And their viscosity all accords with the quadratic function ?B=?+2H/??B2.The viscosity of metallic melts under the magnetic field is proportional to the square of magnetic intensity.Under the horizontal magnetic field,the viscosity of Ga₈₀Fe₂₀,Ga₈₀Co₂₀,Ga₈₀Ni₂₀ and Ga₈₀Cr₂₀ decreases with the increasing temperature,and the viscosity all accords with Arrhenius equation.With the increasing magnetic intensity,their superheated fragility decreases at first,then increases and decreases at last,attributed to the magnetic force and the effect of magnetic field on the entropy.When there is no external magnetic field,with the increasing temperature of liquidus,the fragility of Ga₈₀Fe₂₀,Ga₈₀Co₂₀,Ga₈₀Ni₂₀ and Ga₈₀Cr₂₀ decreases.Compared to the fragility of Ga₈₀Fe₂₀ and Ga₈₀Co₂₀,the fragility of Ga₈₀Ni₂₀ and Ga₈₀Cr₂₀ is smaller.The liquid structures of Ga₈₀Fe₂₀,Ga₈₀Co₂₀,Ga₈₀Ni₂₀ and Ga₈₀Cr₂₀ have been calculated using the method of molecular dynamic simulation.In liquid Ga₈₀Co₂₀ and Ga₈₀Ni₂₀,the atoms of Co and Ni have been enclosed by Ga atoms to form the structure of medium range order.In liquid Ga₈₀Fe₂₀,Fe atoms and Ga atoms distribute randomly.In liquid Ga₈₀Cr₂₀,the Cr atoms have formed the clusters and the clusters have a tendency to separate.The response of viscosity to the magnetic field can be arranged as Ga₈₀Ni₂₀,Ga₈₀Cr₂₀,Ga₈₀Co₂₀,Ga₈₀Fe₂₀ from intense to weak,which can be attributed to the sizes of clusters and the interaction force between particles under the magnetic field.