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在Zr-4合金基础上添加0.1%—0.5%Bi(质量分数)制备成Zr-4+xBi合金,用高压釜腐蚀实验研究了Bi含量对Zr-4+xBi合金在400℃/10.3 MPa过热蒸汽中耐腐蚀性能的影响;用TEM,EDS和SEM观察了合金和合金腐蚀后氧化膜的显微组织.结果表明:随着Bi含量的增加,Zr- 4+xBi合金中第二相的尺寸和形状变化不大,但数量增多,并出现了不同成分的第二相,包括Zr(Fe,Cr)_2,Zr-Fe- Cr-Bi.Zr-Fe- Sn -Bi和Zr-Fe- Cr-Sn-Bi.在Zr -4+0.1Bi合金中检测到了含Bi的第二相,这说明580℃时Bi在Zr- 4+xBi合金α- Zr基体中的固溶度小于0.1%.另外,适量Bi的添加促进了原先固溶在α-Zr基体中Sn的析出.与Zr-4合金相比,在Zr-4中添加0.1%—0.5%Bi后合金的耐腐蚀性能反而下降,并随着Bi含量的增加耐腐蚀性能恶化趋势越显著,这说明Zr-4合金中添加Bi并不能改善合金的耐腐蚀性能,反而产生有害的影响.这应该与含Bi第二相和同时含有Bi,Sn第二相的析出有关.
The Zr-4 + xBi alloy was prepared by adding 0.1% -0.5% Bi (mass fraction) to Zr-4 alloy and the effect of Bi content on the Zr-4 + xBi alloy over 400 ℃ / 10.3 MPa The corrosion resistance of the alloy was investigated by TEM, EDS and SEM.The results show that with the increase of Bi content, the size of the second phase in the Zr-4 + xBi alloy And the second phase with different composition, including Zr (Fe, Cr) _2, Zr-Fe-Cr-Bi.Zr-Fe-Sn-Bi and Zr-Fe-Cr -Sn-Bi. The second phase containing Bi was detected in the Zr-4 + 0.1Bi alloy, which indicated that the solubility of Bi in α-Zr matrix of Zr-4 + xBi alloy was less than 0.1% at 580 ℃. , And the addition of proper amount of Bi promoted the precipitation of Sn in the α-Zr matrix, which had been previously dissolved in solid solution.Compared with Zr-4 alloy, the corrosion resistance of the alloy decreased with addition of 0.1% -0.5% Bi in Zr-4 With the increase of Bi content, the corrosion resistance tends to deteriorate more significantly, which indicates that the addition of Bi in Zr-4 alloy can not improve the corrosion resistance of the alloy, but has a detrimental effect.This should be the second phase containing Bi and containing Bi , Sn precipitation of the second phase there turn off.