几种含铌镍基合金的热腐蚀研究

用硫酸钠沉积法研究了四种镍基合金-Ni-16Cr,Ni-16Cr-2Nb,IN738和537合金-在900～1000℃之间的热腐蚀行为。用热天平测量了热腐蚀动力学曲线,用金相、SEM、电子探针、X 射线衍射和~(3δ)S 示踪法观察和分析了腐蚀产物。研究发现,Ni-16Cr-2Nb 合金中的铌富集在表面氧化膜内,形成 NaNbO_3而降低熔盐中的 O~(2-)浓度,抑制 Cr_2O_3膜与熔盐的反应;但在复杂成份的合金中。铌的上述作用可能促进氧化膜的酸性熔融。鈪同时能促进硫在 Ni-16Cr-2Nb 变形合金晶界上的连续分布,加速内硫化过程。

HOT CORROSION BEHAVIOR OF SOME Ni-BASE ALLOYS CONTAINING Nb

The hot corrosion behavior of four Ni-based alloys—Ni-16Cr,Ni-16Cr-2Nb, IN738 and 537—between 900～1000℃ were studied by the use of Na_2SO_4 deposit. The kinetics curves of hot corrosion were obtained by using a thermobalance. Corrosion products were examined with metallography,SEM,electronic microprobe,X-rays diffraction and ~(36)S tracer.It was found that Nb was enriched in surface oxide scale of Ni-16Cr-2Nb.Nb could decrease the O~(2-) ion activity of Na_2SO_4,melts by the formation of NaNbO_3,and then reaction between Cr_2O_3 scale and the melts was retarded.For multi-component alloys like IN738 and 537,Nb might promote acidic fluxing of the oxide scale.Nb also promoted continuous segregation of sulfur at grain boundaries of Ni-16Cr- 2Nb alloy and speed up the process of internal sulfidation.