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利用静态高压釜腐蚀实验研究了Zr-0.7Sn-0.35Nb-0.3Fe-xGe(x=0.05,0.1,0.2,质量分数,%)系列合金在360℃/18.6 MPa/0.01 mol/L LiOH水溶液中的耐腐蚀性能;利用TEM和SEM分别观察了合金基体的显微组织和氧化膜的显微组织.结果表明:Ge可以显著改善Zr-0.7Sn-0.35Nb-0.3Fe合金在高温高压LiOH水溶液中的耐腐蚀性能,当Ge含量为0.1%时,合金的耐腐蚀性能最佳.在Zr-0.7Sn-0.35Nb-0.3Fe-xGe系列合金中发现尺寸较小的hcp结构的Zr(Fe,Cr,Nb)_2型、Zr(Fe,Cr,Nb,Ge)_2型第二相和尺寸较大的四方结构的Zr_3Ge型第二相.腐蚀220 d的Zr-0.7Sn-0.35Nb-0.3Fe-0.1Ge合金氧化膜致密,厚度较薄,几乎没有微孔隙和微裂纹,ZrO_2柱状晶较多.这说明添加适量的Ge不仅可以有效延缓氧化膜中空位扩散凝聚形成微孔隙和微孔隙发展形成微裂纹的过程,还可以延迟ZrO_2由柱状晶向等轴晶的演化,从而改善合金的耐腐蚀性能.
The corrosion behavior of Zr-0.7Sn-0.35Nb-0.3Fe-xGe (x = 0.05,0.1,0.2, mass fraction,%) series alloy in 360 ℃ / 18.6 MPa / 0.01 mol / L LiOH aqueous solution was investigated by static autoclave corrosion test The corrosion resistance of Zr-0.7Sn-0.35Nb-0.3Fe alloy was observed by TEM and SEM.The results show that Ge can significantly improve the microstructure of Zr-0.7Sn-0.35Nb-0.3Fe alloy in high temperature and high pressure LiOH aqueous solution The corrosion resistance of the alloy is best when the content of Ge is 0.1% .The Zr (Fe, Cr) with small size hcp structure is found in the Zr-0.7Sn-0.35Nb-0.3Fe-xGe series alloy , Nb) _2, the second phase of Zr (Fe, Cr, Nb, Ge) _2 and the larger size of tetragonal Zr_3Ge second phase.The Zr-0.7Sn-0.35Nb-0.3Fe- 0.1Ge alloy oxide film is dense, thin, almost no micro-pores and micro-cracks, ZrO 2 columnar crystals more. This shows that adding an appropriate amount of Ge can not only effectively delay the diffusion of oxide film cohesion formation of microporosity and micro-pore development formation of micro Crack process, but also can delay the evolution of ZrO2 from columnar to equiaxed grains, thereby improving the corrosion resistance of the alloy.