Influence of a Pulse Magnetic Field on the Size and Distribution of Primary Si in Hypereutectic Al-23Si Alloy

摘要

A pulse magnetic field(PMF)was applied on the hypereutectic A1-23%Si alloy of different temperature range(830-780℃,830-730℃,830-700℃,780-700℃,730-700℃)during its solidification processing.The influence of pulse magnetic field on the size and distribution of primary Si was studied.The results show that,the primary Si is very coarse strip,distributs non-unifromly and gathers at the edge of the sample when the alloy solidifies under the condition of no PMF.By applying PMF can significantly refine the primary Si,and make the primary Si distribute uniformly.There has no significant effect on the refinement of primary Si when PMF applied from 830℃to 780℃,indicating that PMF has no outstanding effect on the high temperature liquid metal.Applying PMF from 50℃above the liquidus to 30℃below the liquidus(i.e.from liquid to the initial nucleation stage)can get the best refinement result.The refining mechanism of the pulse magnetic field on the solidification structure of Ai-23%Si alloy was discussed,