NiCoCrAlYTa粘结层与镍基高温合金基体的界面高温互扩散行为

采用真空等离子体喷涂技术(vacuum plasma spraying, VPS)在镍基高温合金GH3128基体表面沉积NiCoCrAlYTa粘结层,并在1 100 ℃进行不同时间的热处理。采用扫描电子显微镜（scanning electron microscopy,SEM）、能谱仪（energy dispersive spectrometer,EDS）等分析NiCoCrAlYTa粘结层与GH3128高温合金界面元素的互扩散行为。结果表明,在热处理过程中,互扩散区(interdiffusion zone,IDZ)和二次反应区(secondary reaction zone,SRZ)的厚度随着热处理时间延长而增大,且在SRZ中明显观察到拓扑密堆(topological close-packed,TCP)相晶粒的生长。Al、Ta、Co元素由NiCoCrAlYTa粘结层向GH3128高温合金扩散,Ni、W、Mo元素由GH3128高温合金向NiCoCrAlYTa粘结层扩散。依据EDS检测的粘结层/基体界面处元素成分,计算出上述元素在界面处的扩散系数,掌握了各元素在高温热处理过程中的扩散速率,揭示了VPS制备的NiCoCrAlYTa粘结层与GH3128高温合金界面处元素在高温下的互扩散规律。

Interdiffusion behavior between NiCoCrAlYTa coating and Ni-based superalloy at high temperature

NiCoCrAlYTa coating was deposited on GH3128 superalloy substrate by vacuum plasma spraying (VPS), and then the specimens were heated treatment for different time at 1100 ℃ was carried. The element interdiffusion behavior was evaluated between the coating and the GH3128 superalloy were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that thicknesses of the interdiffusion zone (IDZ) and the secondary reaction zone (SRZ) increase with the elongation of heat treatment time, and the growth of the topological close-packed (TCP) phases can be observed in the SRZ. Al, Ta and Co elements diffuse from the coating to the substrate, while Ni, W and Mo elements diffuse from the substrate to the coating. According to the EDS results of the content of elements at the interface between the coating and the substrate, the diffusion coefficient of the above elements at the interface can be calculated. Therefore, the diffusion rate of each element can be achieved during high temperature heat treatment process, which discovers the elements diffusion law at the interface between the coating and the substrate.