采用电子束物理气相沉积(EB-PVD)在单晶高温合金DD6基体上沉积NiCrAlYSi涂层。利用X射线衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)以及透射电镜(TEM)等研究了高温扩散过程中NiCrAlYSi/DD6的界面再结晶和互扩散行为。研究结果表明合金表面喷砂处理后的涂层试样经1 323 K真空热处理4 h后,在涂层/合金基体界面出现了厚度约为7 μm的胞状再结晶区;表面未喷砂处理的涂层试样经过50 h后没有出现再结晶,经过75 h后形成了厚度约为15 μm的再结晶区。在大气中静态氧化500 h后,表面未喷砂处理试样在涂层/合金界面形成了厚度约为28 μm的再结晶区,同时在合金基体中形成了厚度约60 μm、以针状拓扑密堆相(TCP)为主的二次反应区(SRZ),TCP中富含W、Re和Ta元素。
In this paper, the NiCrAlYSi coatings are deposited by electron beam physical vapor deposition (EB-PVD) on nickel-based single crystal superalloy DD6. Inter-diffusion and recrystallization behaviors at the coating/superalloy interface of the coated superalloy substrates are investigated at 1 323 K by X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM). The results indicate that a recrystallization zone of ~7 μm thickness is formed at the coating/substrate interface of the blasted sample after 4 h vacuum heat-treatment at 1 323 K. Such recrystallization zone is not observed in the unblasted sample even after 50 h heat-treatment. However, a recrystallization zone of ~15 μm thickness is formed in the sample after 75 h. After 500 h isothermal oxidation in air at 1 323 K, a recrystallization zone of ~28 μm thickness is formed in the unblasted sample. Besides, a so-called secondary reaction zone of ~60 μm, basically consisting of topologically close-packed phase (TCP) needles, is formed in the superalloy. The precipitate of TCP is enriched in W, Re and Ta.
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