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用高压釜腐蚀实验研究了添加0.05%—0.5%Cu(质量分数)对M5(Zr-1%Nb)合金在500℃/10.3 MPa过热蒸汽中耐腐蚀性能的影响;用TEM和SEM分别观察了合金基体和腐蚀后氧化膜的显微组织.结果表明:Cu含量低于0.2%时,随着Cu含量的增加,合金的耐腐蚀性能得到明显改善;继续提高Cu含量则对进一步改善合金耐腐蚀性能的作用不明显.Cu含量不超过0.2%时,Cu主要圈溶在α-Zr基体中;当Cu含量高于0.2%时,Cu除了圈溶在α-Zr基体中之外,其余的Cu主要以Zr_2Cu型第二相析出.固溶在α-Zr基体中的Cu,在α-Zr被氧化后可以延缓氧化膜中空位扩散凝聚形成孔隙和孔隙发展成为微裂纹的过程,增加氧化膜的致密度,从而提高合金的耐腐蚀性能.可见,对M5合金耐腐蚀性能影响起主要作用的是固溶在α-Zr中的Cu,而不是含Cu第二相.
The effect of adding 0.05% -0.5% Cu on the corrosion resistance of M5 (Zr-1% Nb) alloy in 500 ℃ / 10.3 MPa superheated steam was studied by autoclave corrosion test. The corrosion resistance of M5 Alloy matrix and the oxide film after corrosion.The results show that with the Cu content below 0.2%, with the increase of Cu content, the corrosion resistance of the alloy can be significantly improved; continue to improve the content of Cu is to further improve the corrosion resistance of the alloy The effect is not obvious. When the Cu content is less than 0.2%, the main ring of Cu is dissolved in the α-Zr matrix. When the Cu content is higher than 0.2%, Cu is not only dissolved in the α-Zr matrix, Mainly in the second phase precipitated Zr2Cu solid solution in the α-Zr matrix of Cu, α-Zr is oxidized can slow down the diffusion of oxide film after the formation of pores and pores to develop into micro-cracks process to increase the oxide film Density, so as to improve the corrosion resistance of the alloy.It can be seen that the main role of the corrosion resistance of M5 alloy is Cu dissolved in α-Zr, rather than the second phase containing Cu.