螺旋磁场对Sn-Sb合金成分偏析的影响

为了深入研究螺旋磁场解决重力偏析的效果及作用机理,本文选用低熔点Sn-Sb合金,分析不同励磁电流下螺旋磁场对铸锭宏观成分偏析的影响,并与常规条件下及相同工艺参数旋转磁场条件下的凝固组织进行比较.结果表明,螺旋磁场的电磁力分布特点有利于在铸锭内部形成更大区域的均匀搅拌,相比于旋转磁场可以更好地改善铸锭成分的宏观偏析;随着励磁电流的增大,两种磁场改善偏析、细化凝固组织的效果更好;当螺旋磁场励磁电流为100 A时,基本消除铸锭上、下部位由于重力作用导致的成分偏差,β相(SnSb)变得细小且均匀分布在基体内.在金属熔体凝固的过程中施加螺旋磁场可消除重力偏析,效果优于旋转磁场.

Effects of spiral magnetic field on composition segregation of Sn-Sb binary alloy

To study the mechanism of spiral magnetic field and the effect of gravity segregation,low-melting Sn-Sb alloy was selected in this paper to analyze the effects of spiral magnetic field(SMF) on macrosegregation of the ingot at different excitation currents,and these effects were also compared with the effects of conventional condition and rotating magnetic field(RMF) at the same stirring parameters.The experimental results show that the distribution of spiral magnetic field’s(SMF) electromagnetic force is more beneficial to form a well stir in a bigger zone which is more effective to improve the macrosegregation of the ingot than the RMF dose with the same excitation current.A higher excitation current can lead to a more refined solidified structure with lower component segregation for both RMF and SMF.Component difference between the upper and lower part of the ingot due to the gravity is substantially eliminated when the current of RMF is 100 A,and a more refined and irregular primary-precipitated β(SnSb) phase which inlays the matrix structure uniformly will be obtained,while the RMF can’t eliminate the segregation totally and the overall effects are worse than those of the SMF.