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用高压釜腐蚀实验研究了不同Nb含量的Zr-xNb-0.4Sn-0.3Fe(x=0~1,质量分数,%)合金在360℃、18.6MPa纯水,360℃、18.6MPa、0.01mol/LLiOH水溶液以及400℃、10.3MPa过热蒸汽中的耐腐蚀性能,用TEM和SEM分析了合金腐蚀前后的显微组织。结果表明,x从0增加至1时,合金在纯水和过热蒸汽中的腐蚀增重逐渐增加,但在LiOH水溶液中的腐蚀增重减少;Nb具有细化合金再结晶晶粒作用,随着Nb含量的增加,合金中第二相直径相接近,但第二相的面密度和Nb/Fe比增大,当x≤0.2时,第二相主要为不含Nb的ZrFe或含少量Nb的ZrNbFe相,0.3≤x≤1时,主要为ZrNbFe相;合金腐蚀速率越高,氧化膜断面平行裂纹越多,基体/氧化膜界面处呈“菜花”状凸起越严重。探论了Nb含量对Zr-xNb-0.4Sn-0.3Fe耐腐蚀性能影响的机理,认为含Nb第二相的析出量是引起合金耐腐蚀性能差别的主要原因。
The autoclave corrosion experiments were carried out on Zr-xNb-0.4Sn-0.3Fe (x = 0 ~ 1, mass fraction) alloys with different Nb contents at 360 ℃, 18.6MPa pure water, 360 ℃, 18.6MPa, / LLiOH aqueous solution and 400 ℃, 10.3MPa superheated steam corrosion resistance, TEM and SEM analysis of alloy corrosion before and after the microstructure. The results show that when x increases from 0 to 1, the corrosion weight gain of the alloy in pure water and superheated steam increases gradually, but the corrosion weight gain decreases in LiOH aqueous solution. Nb has the effect of recrystallization grain refinement of alloy, Nb content increases, the second phase diameter close to the alloy, but the second phase surface density and Nb / Fe ratio increases, when x ≤ 0.2, the second phase is mainly Nb-free ZrFe or containing a small amount of Nb ZrNbFe phase, the main phase is ZrNbFe phase when 0.3≤x≤1. The higher the corrosion rate is, the more cracks are parallel to the cross section of the oxide film. The more “Cauliflower” bulge appears at the interface between the substrate and the oxide film. The mechanism of the effect of Nb content on the corrosion resistance of Zr-xNb-0.4Sn-0.3Fe was discussed. It is considered that the precipitation of Nb-containing second phase is the main reason that causes the difference of corrosion resistance of the alloy.