亚共晶Al-5.8%Cu合金的非平衡熔化行为

Non-equilibrium Melting Behavior of Al-5.8%Cu Hypoeutectic Alloy

分析了Al 5 8%Cu亚共晶合金在不同加热条件下的DSC试验结果 ,研究了具有不同凝固组织的试验合金的非平衡熔化行为。研究发现 ,其熔化开始温度随加热速度的增大略有升高 ;共晶熔化激活能与凝固组织相关 ,慢速凝固组织的熔化激活能大于快速凝固组织。凝固组织中存在的非平衡共晶在熔化前的加热过程中大部分溶解 ,剩余部分参与共晶熔化 ,溶解的非平衡共晶的量受溶质扩散面积和加热速度的共同作用 ,随加热速度的减小和扩散表面积的增大而增大。

DSC (Differential Scanning Calorimetry) was employed to investigate the melting behavior of Al 5 8%Cu hypoeutectic alloy under the non equilibrium heating conditions. During heating process, most of the non equilibrium eutectic in the solidification structure dissolved due to the diffusion of the solute. The initial melting temperature does not depend on the microstructure, but slightly rises with the increasing of heating rate. The melting activation energy of experiment alloy with different solidification structures was also calculated using Kissinger model. It was found that the melting activation energy with slow solidification structure was higher than that of the rapid one. The dependence of the amount of dissolved non equilibrium eutectic on the heating rate and diffusion interface area was also described and calculated numerically in the present paper. The result was well agreed with the experiment.