21-4NWNb气阀合金高温氧化行为研究

High Temperature Oxidation Behavior of 21-4NWNb Gas Valve Alloy

用X射线衍射、扫描电子显微镜和能量色散光谱仪研究了21-4NWNb合金在750℃空气中氧化后的组织形貌。在750℃的实验静止空气中,合金表面或亚表面形成了一系列的氧化物,合金最外层氧化皮(Fe_(2)O_(3)、Mn_(2)O_(3))和内部氧化物Cr_(2)O_(3).合金的高温抗氧化性取决于表面氧化物层的稳定性,随着氧化时间的延长,前期氧化增重迅速,氧化速率较快,氧化中期,氧化增重及氧化速率均下降,氧化后期合金的氧化增重增长十分缓慢,氧化速率大幅降低至0.0035mg/(cm^(2)·h)。

The microstructure and morphology of 21-4NWNb superalloy after oxidation at 750℃for different time were studied by X-ray diffraction,scanning electron microscope and energy dispersive spectrometer.In the static air at 750℃,a series of oxides were formed on the surface or sub-surface of the alloy,including the external oxide scale(Fe_(2)O_(3),Mn_(2)O_(3))and the internal oxide Cr_(2)O_(3).The high-temperature oxidation resistance of the alloy depends on the stability of the surface oxide layer.With the extension of oxidation time,the oxidation weight increased rapidly in the early stage and the oxidation rate was faster,while in the middle stage,the oxidation weight increased and the oxidation rate decreased,at the later stage of oxidation,the oxidation weight gain of the alloy increased very slowly,and the oxidation rate decreased significantly to 0.0035 mg/(cm^(2)·h).