α+β两相区热处理对Zr-Sn-Nb合金微观组织和腐蚀性能的影响

对Zr-Sn-Nb合金在α+β两相区温度下不同工艺热处理后所得样品，在360 ℃/18.6 MPa纯水环境中进行均匀腐蚀试验，并采用扫描电子显微镜（SEM）观察样品微观形貌、聚焦离子束（FIB）和原子力显微镜（AFM）分析腐蚀后样品表面氧化膜。结果表明，Zr-Sn-Nb合金在α+β两相区温度下热处理时，锆合金中会形成条带状β-Zr第二相，再经过α相区温度最终退火后，β-Zr区域会分解为α-Zr和第二相粒子；经α相区最终退火的样品，在360 ℃/18.6 MPa纯水中的耐腐蚀性能优于未经最终退火的样品；未退火样品中条带状β-Zr第二相区域的氧化膜较α-Zr基体的氧化膜厚，而经过α相区温度退火后β-Zr发生分解，该区域的腐蚀氧化膜出现凹陷。

Effect of Heat Treatment in α+β Phase Field on Microstructure and Corrosion Property of Zr-Sn-Nb Alloy

Uniform corrosion tests were carried out with the specimens prepared by different heat treatments at the temperature in α+β phase field. The surface microstructure of specimens was observed by scanning electron microscope, the corrosion behavior was analyzed by autoclaves, and the oxide layer on the surface after the corrosion test was analyzed by focused ion beam (FIB) and atomic force microscope (AFM). The results show that after the heat treatment in α+β phase field, lamellar β-Zr phase appeares in the Zr matrix, and after the subsequent α phase final heat treatment, the β-Zr phase will be decomposed to α-Zr and discontinuous second phase particles. For the specimens heat treated in α+β phase field, after the α phase final heat treatment, the corrosion resistance under 360 ℃/18.6 MPa pure water condition is better than that of specimens without final heat treatment. The oxide film formed on the β-Zr protrudes on the oxide surface, on the contrary, after α phase final heat treatment, β-Zr decomposes, and the oxide layer is sunken in this area.