Zr(Fe_x,Cr_(1-x))2合金在400℃过热蒸汽中的腐蚀行为

CORROSION BEHAVIOR OF Zr(Fe_x,Cr_(1-x))_2 ALLOYS IN 400℃SUPERHEATED STEAM

用真空非自耗电弧炉熔炼了3种与锆合金中常见第二相粒子成分相同的合金Zr(Fe_x,Cr_(1-x))_2(x=1,2/3,1/3).研究锆合金中第二相粒子的腐蚀行为.第二相合金的粉末在高压釜中经400℃/10.3 MPa过热蒸汽腐蚀不同时间后,利用XRD和能量过滤TEM对腐蚀产物进行了物相分析,结果表明:Cr对第二相合金的氧化速率有很大的影响,增加Cr含量可以提高第二相合金的耐腐蚀性能;由于Fe和Cr在ZrO_2中的固溶度极低,第二相合金被腐蚀形成ZrO_2时,Fe和Cr被排出并形成α-Fe(Cr)和γ-Fe(Cr),最终腐蚀生成(Fe,Cr)_3O_4.不同成分第二相合金的腐蚀行为不同,会对锆合金氧化膜的显微组织演化产生不同的影响,因而也对锆合金的耐腐蚀性能产生不同的影响.

To study the corrosion behavior of second phase particles in zirconium alloys, Zr（Fex, Crl-x）2 （x=1, 2/3, 1/3） metallic compounds which have the same composition as the second phase particles in Zr-4 alloy were prepared by vacuum non--consumable arc melting. XRD and energy filtered TEM were employed for analyzing the corrosion products, the element distribution and grain morphology after corrosion tests of Zr（Fex, Cr1-x）2 metallic compounds powder at 400 ℃ and 10.3 MPa superheated steam with different exposure times. The results show that Cr has a very strong effect on the corrosion resistance of Zr（Fex, Cr1-x）2 metallic compounds, increasing Cr content can improve the corrosion resistance. When Zr（Fex, Cr1-x）2 oxidation starts, zirconium oxide is formed while elements Fe and Cr are expelled from the zirconium oxide due to their low solid solubility in the oxide, α-Fe（Cr） and 3,-Fe（Cr） are formed and then oxidized to the stable corrosion product （Fe, Cr）3O4. The different corrosion behaviors of metallic compounds will affect the microstructure evolution of zirconium oxide layer differently during the corrosion process, and hence affect the corrosion resistance of zirconium alloys.