Effects of Re and Ru Additions on Solidification Partition Coefficients and Solidification Characteristic Temperatures of Nickel Base Single Crystal Superalloys

摘要:

采用双区加热和液态金属冷却相结合的定向凝固方法，制备出4种Re和Ru含量不同的平界面态镍基单晶高温合金，精确测定了近平衡凝固时合金中各元素的平衡分配系数和合金的凝固特征温度。结果表明：Re的添加将显著降低重偏析元素Re、W和Ta的偏析程度，使液相线温度先降低后升高，而固相线温度始终降低；Ru的添加对偏析的影响较小，并略微降低合金的液相线和固相线温度。同时，根据平衡分配系数和凝固特征温度可预测非平衡凝固态单晶合金的元素偏析和凝固缺陷形成倾向

Abstract:

In order to understand the effects of Re and Ru additions on solidification characteristics of nickel base single crystal superalloys, four nickel base single crystal superalloys containing different contents of Re and Ru, were produced by dual heating zone melting and liquid-metal cooling (LMC) directional solidification technique at the withdraw rate of 2 μm/s, and a planar solid/liquid interface was obtained. The equilibrium partition coefficients of each element and solidification characteristic temperatures of experimental alloys were also obtained. Results show that with the increasing of Re content, the segregation degree of high segregation elements Re, W and Ta decreases, the liquidus temperature decreases initially and then increases, while the solidus temperature decreases continuously. The addition of Ru has little influence on the partition of other elements, and slightly lowers the liquidus temperature and solidus temperature of superalloys. In addition, we can effectively forecast the segregation degree of elements and solidification defects of non-equilibrium directional solidified superalloys on the basis of equilibrium partition coefficients and solidification characteristic temperatures