Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu合金在400℃过热蒸气中的耐腐蚀性能

Corrosion Resistance of Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu Alloys in Super-Heated Steam at 400 ℃

采用静态高压釜腐蚀试验研究了Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu（x=0.05~0.5,质量分数,%）合金在400℃,10.3MPa过热蒸气中的耐腐蚀性能,用TEM和SEM分别观察了合金的显微组织和氧化膜的断口形貌。结果表明：当Cu含量不超过0.2%时,合金中析出的第二相主要是尺寸较小的Zr（Fe,Cr,Nb）2型和少量尺寸相对较大的含Cu的Zr3Fe型;当Cu含量超过0.2%时,合金中析出了Zr2Cu型第二相,随着Cu含量的增加,Zr2Cu型第二相尺寸增大,数量增多;在添加0.05%Cu的合金中就有含Cu第二相的析出,说明Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu合金-Zr基体中固溶的Cu含量很低。当Cu含量不超过0.35%时,合金的的耐腐蚀性能基本没有差别;但是当Cu含量达到0.5%时,由于合金中析出了尺寸较大、数量较多的Zr2Cu型第二相,致使合金的耐腐蚀性能变差。

The effect of Cu content on the corrosion resistance of Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu alloys （x=0.05～0.5, mass fraction, %） was investigated in superheated steam at 400 ℃ and 10.3 MPa by autoclave tests. The microstructure of the alloys and the fracture surface of oxide films on the corroded specimens were observed by TEM and SEM, respectively. The results show that when the addition of Cu is below 0.2%, the second phase particles （SPPs） are mainly Zr（Fe,Cr,Nb） 2 in smaller size, and few Zr 3 Fe with Cu. When the addition of Cu is above 0.2%, the SPPs of Zr 2 Cu are precipitated. The Zr 2 Cu particles become larger in size and more in amount with the increase of Cu content. The precipitates containing Cu are found in the alloy even with 0.05% Cu, which indicates that the Cu concentration in α-Zr matrix is very small. Cu addition of 0.05%～0.35% has little effect on the corrosion resistance of the alloys, but when the addition of Cu reaches 0.5%, the corrosion resistance of the alloy decreases, which is the worst one among the alloys.