材料期刊网

将含有0.51％Y和不含Y的两种Fe-Cr-Al合金,在1200℃空气中进行了500小时的氧化实验。用X-射线衍射仪、扫描电镜、电子探针及离子探针对不同氧化时间的试样进行了分析,结果表明,除了初期(约20小时)稍提高Fe-Cr-Al合金氧化速度外,总的说来,钇的添加降低了合金的氧化速度。同时,钇的氧化物分布在以α-Al_2O_3为主的氧化膜中,使得α-Al_2O_3氧化物成为柱状晶,这种构造的氧化膜可经受较大压应力作用,因此在冷热交变过程中氧化膜不易剥落。钇与扩散到基体中的氧优先反应生成Y_2O_3,对阻止合金基体的内氧化及力学性能变坏也起到一定的抑制作用。

The oxidation of Fe-Cr-Al and similar alloys containing 0.51% Y was studied in air at 1200℃ up to 500hrs. The oxide scales were analysed using X-ray diffraction, scanning electron microscope, electron and ion probe microanalysis. It can be seen from the kinetics data obtained that the alloy containing Y has slightly higher oxidation rates at initial stage, but after some 20hrs the weight gain of the alloy drops drastically. It is interesting to find out that the crystals of α-Al_2O_3 scales formed on Fe-Cr-Al-Y alloy are columnar grains perpendicular to the alloy-oxide surface. The oxide film of the yttrium containing alloy can with·stand higher compressive stress than that of the yttrium free alloy. The addition of yttrium to the heat-resistant Fe-Cr-Al alloy may remarkably enchance the adhesion of the oxide scale formed at elevated temperatures. Yttrium added to the alloy is concentrated at grain boundaries and will preferentially react with oxygen diffusing into the alloy matrix. The formation of Y_2O_3 at grain boundaries will prevent internal oxidation of the alloy.