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建立了梯度磁场下金属熔体中晶粒迁移的一般动力学模型,导出了磁场对导电熔体黏度的影响规律,得到了迁移速度的解析解和迁移距离的分析解.导电熔体的有效黏度随磁场强度的平方成线性递增关系.迁移速度达到终极速度的时间为10-3s数量级.终极速度随着磁场强度的增加而迅速减小,表明强磁场对晶粒迁移有抑制作用.迁移距离和迁移率与磁场分布密切相关.为观察初晶硅的迁移状况,将Al-18wt%Si合金在650℃保温60min后,施加强梯度磁场(Bz=5T,BzdBz/dz=-224T2.m-1)对熔体作用不同时间并淬火,结果表明,晶粒半径大于等于40μm的初晶硅在120s内大部分完成迁移,与理论计算符合.
The general kinetic model of grain migration in metal melt under gradient magnetic field was established and the influence law of magnetic field on the viscosity of conductive melt was deduced.The analytic solution of migration velocity and analytic solution of migration distance were obtained.The effective viscosity With the square of the magnetic field strength increasing linearly.The migration velocity reaches the ultimate speed of 10-3s on the order of magnitude.The ultimate velocity decreases rapidly with the increase of the magnetic field strength.The results show that the strong magnetic field can inhibit the grain migration.The migration distance and The mobility is closely related to the magnetic field distribution. To observe the migration of primary Si, a strong gradient magnetic field (Bz = 5T, BzdBz / dz = -224T2.m-1 ) On the melt at different times and quenching, the results show that the primary crystal grain size greater than or equal to 40μm within 120s most of the migration, complete with theoretical calculations.