论文部分内容阅读
通过等温氧化及循环氧化实验研究了活性元素Sc对CoNiCrAl合金高温氧化动力学、氧化层/基体界面结合力的影响。在1150℃温度下进行了100次1 h循环氧化实验及5,30,50,640,1000 h等温氧化实验。结果表明:添加活性元素Sc能明显降低氧化膜的生长速度,改善氧化层/基体界面结合力,Sc元素添加量的不同对合金高温氧化行为的影响也不同。等温氧化中,原始合金的氧化速率常数为2.5×10-5μm2·s-1,添加0.1%Sc(原子分数,下同)的合金的氧化速率常数降低到原始合金的22.2%,添加0.2%Sc元素的合金的氧化速率常数降低到原始合金的44.4%。原始合金经过5 h等温氧化后的剥落比例就达到35%,经过30 h等温氧化后剥落比例达到95%;添加Sc元素之后,在氧化时间低于640 h时,氧化层的最大剥落比例为11.6%;当氧化时间达到1000 h时,添加0.1%Sc元素的合金的氧化层剥落比例增加到23.6%,添加0.2%Sc元素的氧化层剥落比例增加到68.5%。在循环氧化实验中,原始合金在循环氧化实验中经过1次循环之后重量就出现下降,而添加0.1%Sc及0.2%Sc元素的合金分别经过25和53次循环之后重量才开始下降。相对于原始合金在循环氧化过程中观察到的氮化现象,添加Sc元素的合金基体组织完好,没有受到破坏。
The effects of the active element Sc on the oxidation kinetics of the CoNiCrAl alloy at high temperature and the adhesion between the oxide layer and the matrix were investigated by isothermal oxidation and cyclic oxidation experiments. 100 cycles of 1 h cyclic oxidation and 5, 30, 50, 640 and 1000 h isothermal oxidation experiments were carried out at 1150 ℃. The results show that the addition of Sc can significantly reduce the growth rate of oxide film and improve the adhesion of oxide / matrix interface. The effect of Sc addition on the oxidation behavior is also different. In the isothermal oxidation, the oxidation rate constant of the original alloy is 2.5 × 10-5μm2 · s-1. The oxidation rate constant of the alloy with addition of 0.1% Sc (atomic fraction) is reduced to 22.2% of the original alloy. 0.2% Sc The oxidation rate constant of the elemental alloy decreased to 44.4% of the original alloy. The percentage of exfoliation of the original alloy reached 35% after 5 h of isothermal oxidation and 95% after 30 h of isothermal oxidation. The maximum exfoliation ratio of the oxide layer was 11.6 after the addition of Sc, when the oxidation time was less than 640 h %. When the oxidation time reaches 1000 h, the proportion of oxide layer exfoliated in the alloy containing 0.1% Sc increases to 23.6%, and the proportion of oxide layer exfoliated with 0.2% Sc increases to 68.5%. In the cyclic oxidation experiment, the weight of the original alloy decreased after one cycle in the cyclic oxidation experiment, and the weight of the alloy began to drop after 25 and 53 cycles respectively after adding 0.1% Sc and 0.2% Sc. Compared with the nitriding observed during the cyclic oxidation of the original alloy, the alloy matrix with Sc element was well-organized and undamaged.