强磁场对Al-12.6%Si合金变质效果影响

Effect of high magnetic field on modification of Al 12.6%Si alloy

研究了强磁场对共晶铝硅合金变质效果的影响.对共晶A l-12.6%S i合金进行N a盐变质处理,发现施加强磁场的条件下,在变质剂反应温度下保温20 m in,共晶硅细化,并呈现一定程度的粒状化,其变质效果明显优于不施加强磁场.760℃下延长保温时间至40 m in,未施加强磁场条件下的试样出现严重的变质衰退现象,施加强磁场的试样变质衰退现象相对较轻.在施加强磁场条件下,即使保温40 m in,其变质效果也优于不施加强磁场时保温20m in时的,即强磁场具有一定的延长变质有效时间的作用.分析认为强磁场抑制对流是其中的原因之一.

Effects of high magnetic field on Al-12.6%Si alloy modification were studied, it is found that the sample modified by Na-salt is kept at the temperature of the modification reaction for 20 rain under the condition of high magnetic field, eutectic Si is refined and the modification effect is better than that under the condition without high magnetic field. Moreover, when the sample without high magnetic field is kept at the temperature of 760℃ for 40 min, the modification effect declines. However, the modification effect of the sample with high magnetic field at the temperature of 760℃ for 40 min is better than that without high magnetic field for 20 minutes. In other words, high magnetic field can protract the effective time of the modification. It is thought that it is the reason of the static magnetic field controlling the convection of the melt.