新型镍基单晶高温合金的显微组织与力学性能

摘要

采用高通量的合金设计方法设计一种新型镍基单晶高温合金CSU-B2，并对该合金进行了一系列的研究。结果表明：该合金在铸态下树枝晶分布均匀，枝晶间距约为500µm，没有三次枝晶出现。通过对合金进行固溶和时效处理，合金中的γ′析出相呈现方块状，平均颗粒尺寸为0.5~0.8µm。在1100和1150℃下对合金的抗氧化性能进行研究发现，试样单位面积质量随时间的变化遵循类抛物线的规律，在氧化层的下面都存在着γ′相消失的区域。最后对合金的高温拉伸性能进行了表征，在760℃时，合金的屈服强度为706 MPa；在980℃时，合金的屈服强度为484 MPa。在两个温度下，试样的断裂为两种不同的机制。%A new nickel-base single crystal superalloy named CSU-B2 was designed by high-throughput alloy design method and a series of investigations were done to characterize the superalloy. The results show that the primary dendrites are uniformly distributed and the spacing size in the as-cast alloy is about 500 μm, where tertiary dendrite is absent. After solution and ageing treatments, theγ′prime precipitates are cuboidal-shaped and the average size is 0.5−0.8μm. The oxidation-resistance property of the new alloy is evaluated at 1100 and 1150℃, the results show that the oxide growth of the new alloy obeys the parabolic law for both under isothermal and cyclic oxidation, and there both have aγ′free zone under the oxide scale. The yield strengths under the temperature of 760 and 980℃are measured to be 706 and 484 MPa, respectively, and two different mechanisms govern the failure processes.