采用高能微弧合金化技术,通过控制输出功率、电压、沉积时间等工艺参数,成功地在K3合金表面制备致密的Ni3A1(Cr) 超细晶合金化层.合金化层与基体之间是冶金结合、且制备过程对K3基体的热影响很小.在900℃空气中氧化400 h的结果表明, Ni3Al(Cr)合金化层比相应的铸态Ni3Al(Cr)电极和K3高温合金具有更好的高温氧化性能,它形成的富Al2O3氧化膜连续致密、粘附性良好,这得益于晶粒细化增加了短路扩散路径,降低了形成富Al氧化膜所需的临界Al含量.
Abstract: High energy micro-arc alloying process was successfully used to prepare a compact microcrystalline Ni3Al(Cr) coating on the type K3 superalloy using a Ni3Al(Cr) rod as deposition electrode, with a metallurgical bonding between the coating and the substrate alloy. The preparation process was accompanied with a minimal thermal distortion or microstructural changes of the K3 substrate. A splashing appearance was observed on the surface of coatings. The air oxidation experiments at 900oC indicated that the coated K3 exhibited a better oxidation resistance than the uncovered K3 and the cast Ni3Al(Cr) electrode, due to the formation of a continuous, compact and adhesive Al-rich scale. The microcrystallization of Ni3Al(Cr) coatings enhances short-circuit diffusion paths and thus reduces the critical Al content for the formation of a continuous Al2O3 scale.
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