两种MCrAlY涂层/DD6合金的循环氧化和互扩散行为

在DD6单晶高温合金基体上,利用电子束物理气相沉积(EB-PVD)技术制备Ni Co Cr Al Y涂层,采用低压等离子喷涂(LPPS)技术制备Ni Co Cr Al YHf Si涂层,通过扫描电镜(SEM)、X射线能谱(EDS)、X射线衍射(XRD)、电子探针显微分析(EPMA)等手段研究了在1100℃下的热循环氧化和互扩散行为。结果表明,涂层显著提高了DD6基体的抗氧化能力,经100h的循环氧化后,涂层表面氧化层主要成分仍为α-Al2O3,依然发挥着较好的抗氧化保护作用。这两种涂层与基体之间形成了互扩散区(IDZ)和二次反应区(SRZ),IDZ和SRZ的厚度均随着循环氧化时间延长而增大;SRZ中析出的棒状与颗粒状的拓扑密堆相(TCP)含有W、Re、Mo等高熔点元素,其质量分数分别高达37.51%、14.22%和10.61%,TCP含量随着氧化时间而增多。活性元素Si、Hf对涂层中富Cr相和TGO的增长速率均有一定的抑制作用。

Thermal Cyclic Oxidation and Inter-Diffusion Behaviors of MCrAlY-Coated Single Crystal Superalloy DD6

Two types of MCrAlY coatings NiCoCrAlY and NiCoCrAlYHfSi were deposited on DD6 specimens by electron beam physical vapor deposition (EB-PVD) and low pressure plasma spray (LPPS) respectively.The coating surface,cross-section morphologies and phase structures of the specimens were investigated by scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),electron probe micro-analyzer (EPMA) and X ray diffraction (XRD) after 1100℃ cyclic oxidation for different time.The utilization of NiCoCrAlY and NiCoCrAlYHfSi coatings prominently enhance the oxidation resistance of DD6 alloy.After 100h oxidation,α-Al2O3 is still the major phase in the oxide scales formed on the coated specimens.Inter-diffusion occurs between the coatings and the substrate,which leads to the formation of the interdifusion zone (IDZ) and second reaction zone (SRZ).The rod-like TCP phase and the granular TCP phases precipitated in the SRZ,which are rich in W,Re,Mo.Reactive elements (RE) Si,Hf have suppression action on the formation of Cr-rich phase and the growth rate of TGO.