Cu对Zr-2.5Nb合金在500℃/10.3 MPa过热蒸汽中腐蚀行为的影响

EFFECT OF Cu-ADDITION ON THE CORROSION BEHAVIOR OF Zr-2.5Nb ALLOYS IN 500℃/10.3 MPa SUPERHEATED STEAM

添加微量合金元素Cu的Zr-2.5Nb-xCu(x=0.2,0.5,质量分数,%)合金样品,经β相水淬、冷轧变形及580℃,50 h和620℃,2 h退火处理,在静态高压釜中进行500℃/10.3 MPa的过热蒸汽腐蚀实验.利用SEM和TEM研究了氧化膜截面的显微组织.结果表明,添加少量Cu可以提高Zr-2.5Nb合金的耐腐蚀性能;合金的耐腐蚀性能与氧化膜中的柱状晶的生长及形态有关,添加合金元素Cu有利于提高锆合金氧化膜中柱状晶比例.并使柱状晶尺寸增大且排列有序,从而提高锆合金的耐腐蚀性能.

Zr-2.5Nb-xCu （x=0.2, 0.5, mass fraction,%） specimens were annealed at 580 ℃ for 50 h and 620℃ for 2 h afterβ-quenching and cold rolling, and then corroded in autoclave with 500 ℃ /10.3 MPa superheated steam. SEM and TEM equipped with EDS were employed to investigate their corrosion behaviors through analyzing the microstructures of the fracture surface of the oxide layers or of the cross-section of oxide layers. It was found that the addition of copper can improve the corrosion resistance of Zr-2.SNb alloy, which is closely related to the increases in the fraction and size of columnar grains in the oxide film.