定向凝固Al-38.5%Cu合金中带状组织的形成机理

Band Structure Formation Mechanism in Directionally Solidified Al-38.5%Cu Alloy

在温度梯度为260 K·cm^(-1)和凝固速率为1μm·s^(-1)条件下,对Al-38.5%Cu合金凝固组织中存在的Al_2Cu单相和Al/Al_2Cu共晶相交替生长带状组织的形成机理进行了研究。结果表明:带状组织的产生与合金定向凝固界面前沿的溶质分布有关,形成的原因是合金未达到稳态凝固,凝固速率和合金成分一直处于变化之中;在单相和共晶相的带状组织中,合金凝固速率在单相中随着界面前液相溶质含量的增加而逐渐减小,而在共晶相中随着界面前沿液相溶质含量的增加而逐渐增大。

The formation mechanism of the band structure formed during the alternative growth of single phase Al2Cu and eutectic phase Al/Al2Cu in solidified microstructure of Al-38.5%Cu alloy was studied when the growth rate was 1μm·s^（-1） and the temperature gradient was 260 K·cm^（-1） in liquid.The results show that the formation of band structure was related to the solute distribution ahead of solid-liquid interface due to the changes of the growth rate and alloy composition during directional solidification.With the increase of the liquid solute content of the single phase,the solidification rate of the alloy decreased,but in the growth of coupled eutectic phase the solidification rate increased.