雾化工艺对Al-Si合金液滴凝固组织的影响

Effects of Atomization Processing Parameters on Microstructure of Atomized Al-Si Alloy Droplets

将雾化合金液滴的传热与运动方程相耦合,对合金的冷却过程进行研究,探讨液滴尺寸、气体初始速度、熔体过热度等参数对合金冷却过程及粉末微观组织的影响,并结合A390合金进行了计算。结果表明,随着液滴尺寸减小,所获得的冷却速度及过冷度增大;当液滴尺寸足够小时,液滴温度的变化趋势及合金液滴的组织将发生突变;增加雾化气体的初始速度,降低熔体过热度,可以抑制初生相的析出,有利于细化合金的组织。

The cooling process of the Al-Si alloy were analyzed by a model,in which the heat transfer equation of atomized alloy droplets coupling with motion equation was considered,to understand effects of droplet size,initial gas velocity,super-heat of the melt on cooling process and microstructure of the A390 alloy.It is found that,with decreasing in size of droplet,the obtained cooling rate and under-cooled rate are raised.When the droplet size is decreased to below a critical size,temperature change and microstructure of the droplets are sharply transformed.Precipitation of primary phase can be restrained by increasing initial velocity of atomized gas and decreasing superheating rate of melt,which is beneficial to the refinement of microstructure of Al-Si alloy.