采用静态高压釜腐蚀实验研究了Zr-0.80Sn-0.34Nb-0.39Fe-0.1Cr-xCu(x=0.05-0.5, 质量分数, %)合金在500 ℃, 10.3 MPa过热蒸汽中的耐腐蚀性能, 利用TEM观察了合金的显微组织. 结果表明: 添加(0.05-0.5)Cu对合金在500 ℃过热蒸汽中的耐腐蚀性能影响不大. 当x≦0.2时, 合金中的第二相主要为 hcp结构的Zr(Fe, Cr, Nb)2和含Cu的正交结构的Zr3Fe; 当x>0.2时, 除了Zr(Fe, Cr, Nb)2和含Cu的Zr3Fe外, 还有四方结构的Zr2Cu析出. Zr(Fe, Cr, Nb)2比较细小, 而含Cu第二相的尺寸较大. 即使在添加0.05Cu的合金中也有含Cu第二相析出, 说明Cu在该合金α-Zr基体中的固溶量很低. 因此, 添加(0.05-0.5)Cu对该合金在500 ℃过热蒸汽中的耐腐蚀性能影响不大的原因可能与固溶在α-Zr基体中的 Cu含量低有关.
The effect of Cu content on the corrosion resistance of Zr-0.8Sn-0.34Nb-0.39Fe-0.1Cr-xCu alloys (x=0.05-0.5, mass fraction, %) was investigated in superheated steam at 500 ℃ and10.3 MPa by autoclave tests. The microstructures of the alloys are observed by TEM. The results show that (0.05-0.5)Cu addition has little effect on the corrosion resistance of the alloys. When x is below 0.2, the precipitates Zr(Fe, Cr, Nb)2 with hcp structure and Zr3Fe containing Cu with orthorhombic structure are detected. When x is above 0.2, besides Zr(Fe, Cr, Nb)2 and Zr3Fe containing Cu, the precipitate of Zr2Cu with tetragonal structure is also detected. Zr(Fe, Cr, Nb)2 precipitates are smaller than the precipitates containing Cu in size. The precipitates containing Cu are found in the alloy even with 0.05Cu, indicating that the Cu content in α-Zr matrix is very small. Therefore, the reason that the Cu content has little effect on the corrosion resistance of the alloys is maybe related to the lower Cu content in α-Zr matrix.
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