定向凝固Al-40%Cu共晶合金的组织特性

Microstructure of Directional Solidification Al-40%Cu Eutectic Alloy

利用垂直Bridgman法结合液态金属冷却法在恒定的液相温度梯度(GL=250 K/cm),凝固速率由2μm/s到490μm/s之间对Al-40%Cu合金进行定向凝固实验。结果表明:Al-40%Cu合金在低速下组织为全耦合的片层共晶结构,但当速率增加时,合金组织中出现一定量的初生Al2Cu相,凝固速率对合金共晶片层间距的影响通过实验结果分析。在实验的定向凝固速率范围内,发现平界面和胞状界面生长的两种共晶界面形态,并且不管是在哪种共晶界面形态下,共晶层片间距和凝固速率的关系都符合函数关系:λ2ν=常数,利用JH模型计算得到常数C的值为12.85μm3/s。

The directional solidification experiments of Al-40% Cu alloy were conducted with a constant liquid phase temperature gradient （GL=250 K/cm） and the solidification rate range from 2 μm/s to 490 μm/s using a Bridgman method with liquid metal cooling （LMC） technique. The results show that the microstructure of Al-40%Cu alloy in low growth rate is a coupled lamellar eutectic. When the solidification rate increases, a few of primary Al2Cu phases are obtained. The effect of solidification rate on the alloy eutectic lamellar spacing was investigated by experimental. Two types of the eutectic interfacial morphologies, planar and cellular, were indentified in the experimental range of directional solidification rate. Whether it is in what kind of eutectic interfacial morphologies, the eutectic lamellar spacing and solidification rate can meet the function relations of λ^2v=constant, and the constant is 12.85 μm3/S using JH model calculated.