摘要
通过熔炼、热轧、冷轧和退火等工艺制备了 Zr-0.75Sn-1Nb-0.35Fe-0.15Cr(质量分数,％)合金板状样品,采用静电加速器在300 ℃下对样品进行注量为1.02×1015和5.1×1015 ions/cm2(对应辐照损伤剂量分别为1和5 dpa)的Ar+辐照,然后将未辐照和辐照样品置于360 ℃/18.6 MPa/0.01 mol·L-1 LiOH水溶液中腐蚀90 d,利用SEM和TEM表征分析了辐照前后合金基体显微组织和腐蚀后氧化膜截面显微组织.结果表明,辐照前Zr-0.75Sn-1Nb-0.35Fe-0.15Cr合金为完全再结晶组织,晶粒呈等轴晶,第二相主要为fcc和hcp结构的Zr(Fe,Cr,Nb)2,尺寸主要在50～100 nm范围内;辐照后,合金内形成了<a>型位错环,第二相发生了完全非晶化,但未发现第二相中元素向基体扩散现象.腐蚀90d后,辐照样品的氧化膜厚度小于未辐照样品,说明Ar+辐照在一定程度上降低了合金腐蚀初期的腐蚀速率.分析认为,Ar+辐照能延缓氧化膜显微组织的演化,降低氧化膜中的等轴晶占比和裂纹数量,同时辐照诱导的非晶化第二相的氧化更慢,使氧化膜更具保护性,从而降低合金的腐蚀速率.
Abstract
Zr-0.75Sn-1Nb-0.35Fe-0.15Cr(wt％)alloy plates were prepared by smelting,hot rolling,cold rolling and annealing techniques successively.The samples were then irradiated on an electrostatic accelerator with Ar+to a influence of 1.02×1015 and 5.1 × 1015 ions/cm2(corresponding to 1 dpa and 5 dpa,respectively)at 300 ℃.Both the unirradiated and irradiated samples were exposed to 360 ℃/18.6 MPa/0.01 mol/L LiOH aqueous solution for 90 d.The microstructures of the alloy matrix before and after irradiation and the oxide film formed after corrosion were characterized by SEM and TEM.The results show that before irradiation the alloy is fully recrystallized and the grains are equiaxed.The second phase particles are mainly Zr(Fe,Cr,Nb)2 with a fcc or hcp structure,and their size is within the range of 50-100 nm.After irradiation,<a>-type dislocation loops were observed in the irradiated region of the alloy,and the second phase particles are completely amorphous,but the element diffusion from the second phase particles to the matrix is not found.After corrosion for 90 d,the oxide film of the irradiated samples is thinner than that of the unirradiated sample,indicating that Ar+irradiation decreases the corrosion rate of the alloy to some extent at early stage of corrosion.This can be explained by the fact that Ar+irradiation could delay the microstructural evolution of oxide film,including reducing the proportion of equiaxed grains and the number of cracks in the oxide film,as well as slowing down the oxidation of amorphous second phase particles induced by irradiation,thus enhancing the protectiveness of the oxide film.
基金项目
国家重点基础研究发展计划(2022YFB1902400)
国家自然科学基金(52201079)
NETL
NSTL
万方数据