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本文研究了钇对铸造镍基高温合金IN—939热腐蚀性能的影响,采用75％Na_2SO_4—25％NaCl为付蚀介质的坩埚法,在温度为850℃与900℃,时间从10小时到300小时的范围内进行实验。 从热付蚀减重及渗透深度测得的动力学曲线表明:钇能改善合金热付蚀性。对热付蚀产物进行了金相显微镜和扫描电镜观察以及电子探针与X射线衍射分析。观察到含钇合金付蚀层的表面形貌与不含钇合金有明显区别,IN—939合金表面上形成的付蚀层为氧化铬和硫化铬等的多层结构,其下为铬的贫化区;而IN—939Y表面付蚀层是由大量的氧化铬少量的TiO_2,α—Al_2O_3及微量Y_2O_3、YCrO_3与硫化物组成。腐蚀层下没有贫铬现象,而出现贫钛区与沿晶界的内氧化物以及钇与钛的硫氧化物的分散质点。

The effect of yttrium on hot corrosion behaviour of east Ni-base superalloy IN-939 exposed to 75％Na_2SO_4+25％NaCl at 850℃ and 920℃, for 10hrs to 300hrs has been investigated by crucible test method in the present work. The kinetic curves obtained by measuring the weight losses and depths of penetration due to hot corrosion show that the addition of yttrium to IN-939 increases the resistance against hot corrosion of the alloy. The product of hot corrosion is studied by optical microscope, scanning electron microscope, electron microprobe as well as X-ray diffraction techniques. The morphology of corrosion product layer on the surface of IN-939 Y is different from that of IN-939 without yttrium. The corrosion product on the surface of 1N-939 alloys is found to be composed of chromium oxide and sulphide. The region just below is depleted in chromium. The corrosion product on the surface of IN-939 Y alloy consists mainly of Cr_2O_3 with some TiO_2, α-Al_2O_3 and traces of Y_2O_3, YCrO_3 and sulphides. But instead of depletion in Cr, a region depleting in Titanium, with internal oxides along grain boundaries and dispersed oxysulfide particles of yttrium and titanium is observed.