添加2 wt%Cu对Zr-4合金显微结构和耐腐蚀性能的影响

EFFECT OF 2 wt%COPPER ADDITION ON MICROSTRUCTURE AND THE CORROSION BEHAVIORS OF ZIRCALOY-4 ALLOY

研究了在Zr-4合金中添加2wt%Cu的合金显微组织及其在500℃和10.3 MPa过热蒸汽中的耐腐蚀性能。结果表明,该合金经过热轧、冷轧以及经2 h、580℃真空退火处理后,得到以α-Zr为基体的显微组织,合金中主要存在四方结构的Zr_2Cu和密排六方结构的Zr(Fe,Cr,Cu)_2第二相,Zr_2Cu相有长度1～4μm、厚度约1μm的片状和直径300～500 nm的球形两种形态,并且都会富集一定量的Fe元素。在10.3 MPa、500℃过热水蒸汽中,添加2 wt%Cu的Zr-4合金不发生疖状腐蚀,表明Cu是改善锆合金耐疖状腐蚀性能的有益元素。

The effects of the 2 wt% copper addition on microstructures and the corrosion behaviors of Zirealoy-4 alloys in the 500 °C superheated steam of 10.3 MPa were investigated. The main phase was α-Zr after hot rolled, cold rolled and subsequent vacuum annealing treatment （580 ~C for 2 h）. Furthermore, tetragonal-Zr2Cu and hexagonal-Zr （ Fe, Cr, Cn） 2 precipitates were observed by TEM. Enrichment of Fe element was found in lamellar （about 1 -4 μm and 1 μm in length and thickness, respectively） and spherical （300 -500 nm in diameter） Zr2Cu phases. Nodular corrosion was not observed in Zr-4-2Cu after 500 h corrosion in 500 ° C superheated steam of 10.3 MPa, indicating that Cu was beneficial to improving the nodular corrosion resistance of Zircaloy alloy in the environment stated above.