真空热处理对NiCrAlY涂层组织与性能的影响

Effect of vacuum heat treatment on microstructure and property of NiCrAlY coating

采用电弧离子镀（AIP）技术在TC4（Ti-6Al-4V）钛合金表面制备NiCrAlY涂层。利用扫描电镜（SEM）、透射电镜（TEM）、能谱（EDS）分析、X射线衍射分析（XRD）及维氏硬度测量试验研究真空热处理对NiCrAlY涂层组织与性能的影响。结果表明：真空热处理后涂层沉积残余应力得到有效释放，涂层平均晶粒尺寸从沉积态的200 nm增加至950℃真空热处理后的500 nm；真空热处理过程中发生β→γ′→γ相转变，γ′分布于β晶界或γ晶粒内；γ晶粒内析出的γ′相呈细小弥散分布，与基体γ保持共格起到强化作用；经700-750℃真空热处理后，涂层可获得最佳的析出强化效果。

NiCrAlY coating was deposited on TC4 titanium alloy by arc ion plating （AIP）. The effect of vacuum heat treatment on the microstructure and properties of NiCrAlY coating were studied by SEM, TEM, EDS, XRD and Vickers hardness test. The results show that, during the vacuum heat treatment, the deposition residual stress of the coating can be released effectually. The average grain size of the coating increases from 200 nm for the as-deposited state to 500 nm for the vacuum heat-treated state at 950 ℃. β→γ′→γ phase transformation happens during the vacuum heat treatment. γ′phase distributes along the β grain boundaries or in the γ grains. The fine and dispersing γ′ phase in the γ grains is coherent with the substrate, which is able to strengthen the coating substrate. The best precipitation hardening effect for NiCrAlY coating can be obtained after vacuum heat treatment at 700-750℃.