【摘要】 探究了应用温度对含Pt-Al涂层的第三代低成本单晶高温合金蠕变行为的影响。在1100℃/137 MPa、1120℃/137 MPa和1140℃/137 MPa条件下观察蠕变损伤。结果表明：在所有测试条件中，裸基体高温合金均优于带涂层高温合金。在1100℃/137 MPa下进行测试时，蠕变寿命最明显地缩短了50%。在更高温度（1120和1140℃）下，Pt-Al涂层向单晶高温合金基体的裂纹扩展速度减慢，从而减少了力学性能的下降，涂层裂纹的尖端氧化和铝扩散形成了氧化物，而不是渗透到单晶基体中，导致涂层下基体的微结构退化缓慢。然而在1100℃时，涂层/单晶合金基底的微观结构由于铝的内部扩散而退化。这种扩散机制使有害的拓扑密堆相在1100℃左右形成。在1120和1140℃时，涂层下单晶合金基底的位错与内部高温合金的位错相比保持相对不变。与此相反，涂层下基底的位错网络变得稀疏，在1100℃时切割成相的超位错数量增加。更多还原

【Abstract】 The influence of applied temperatures on the creep rupture life of the third-generation low-cost single crystal(SX)superalloy with Pt-Al coating was evaluated. The creep damage was observed under the conditions of 1100 ℃/137 MPa, 1120 ℃/137MPa, and 1140 ℃/137 MPa. Results show that the properties of bare superalloy outperform those of coated superalloy under all test conditions. The most significant reduction in creep life reaches 50% when the test condition is 1100 ℃/137 MPa. At higher temperatures(1120 and 1140 ℃), the crack propagation rate in Pt-Al coatings to SX superalloy substrate decreases, thereby reducing the degradation degree of mechanical properties. Instead of the penetration into SX substrate, tip oxidation and Al diffusion of the coating cracks cause the formation of oxides, therefore leading to the slow degradation in microstructures of the substrate beneath the coating. At 1100 ℃, however, the microstructure of coating/SX superalloy substrate degrades due to the Al internal diffusion. This diffusion mechanism promotes the formation of harmful topologically close packed phases around 1100 ℃. At 1120 and 1140 ℃, the dislocation of SX superalloy substrate beneath the coating is relatively unchanged, compared to that in the inner superalloy. In contrast, the dislocation network of the substrate beneath the coating becomes sparse, and the number of superdislocations cutting into γ′ phases increases at 1100 ℃.更多还原