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杨忠波 《稀有金属材料与工程》2018,47(3):794-798
采用不同的热处理工艺制备出Zr-0.8Sn-1Nb-0.3Fe合金板材,用OM、TEM分析了合金样品的显微组织,用静态高压釜进行了360℃/18.6MPa/0.01mol/LLiOH水溶液和400℃/10.3MPa蒸汽腐蚀试验。结果表明,随着热轧温度从600℃增加至700℃,第二相分布均匀性逐渐变差,第二相主要为C14型HCP-Zr(Nb,Fe)2;热轧前时效改善第二相分布均匀性的同时,促进Nb的扩散,相应增加了βNb的数量,延长最终退火时间对第二相分布影响不大,但增加了第二相中的Nb/Fe比;合金在两种水化学介质中的耐腐蚀性能随热轧温度升高而降低,热轧前时效能改善合金的耐腐蚀性能,延长最终退火时间,提高了合金在LiOH溶液中的耐腐蚀性能,但对合金在过热蒸汽中腐蚀不利;分析了显微组织与耐腐蚀性能的关系,认为第二相尺寸分布、Nb含量是影响Zr-Sn-Nb-Fe锆合金耐腐蚀性能差异的主要原因。 相似文献
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采用不同的热处理工艺制备出Zr-0.8Sn-1Nb-0.3Fe合金板材试样,用OM、TEM分析了试样的显微组织,用静态高压釜进行了360℃/18.6 MPa/0.01 mol/L LiOH水溶液和400 ℃/10.3 MPa蒸气腐蚀试验。结果表明,随着热轧温度从600 ℃增加至700 ℃时,第二相分布均匀性逐渐变差,第二相主要为C14型HCP-Zr(Nb, Fe)_2;热轧前时效改善第二相分布均匀性的同时,促进Nb的扩散,相应增加了βNb的数量,延长最终退火时间对第二相分布影响不大,但增加了第二相中的Nb/Fe比;合金在2种水化学介质中的耐腐蚀性能随热轧温度升高而降低,热轧前时效能改善合金的耐腐蚀性能,延长最终退火时间提高了合金在LiOH溶液中的耐腐蚀性能,但对合金在过热蒸气中腐蚀不利;分析了显微组织与耐腐蚀性能的关系,认为第二相尺寸分布、Nb含量是引起Zr-Sn-Nb-Fe锆合金耐腐蚀性能差别的主要原因。 相似文献
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将添加不同Cu、Nb含量的Zr-Nb-Cu合金在500℃/10.3MPa过热蒸汽条件下腐蚀,用TEM和SEM研究合金腐蚀后生成氧化膜的显微组织。结果表明:添加Nb或Cu元素总含量较低时,Zr-Nb-Cu合金在500℃/10.3MPa过热蒸汽中会出现较严重的不均匀腐蚀。Zr-0.2Nb-0.2Cu和Zr-0.2Nb-1.0Cu合金表现出较好的耐腐蚀性能;Zr-0.2Nb-Cu合金中的Cu含量达到0.2%(质量分数)后,能够完全抑制不均匀腐蚀现象的发生,但在实验条件下继续提高Cu含量对其耐腐蚀性能的影响作用不大。锆合金腐蚀生成氧化膜中的微结构,特别是微孔洞、微裂纹等缺陷的形成与合金元素及第二相的氧化过程密切相关。Nb元素的存在会延缓Zr_2Cu相的氧化及其氧化物的扩散迁移,抑制氧化膜中裂纹的产生,延缓氧化膜中柱状晶向等轴晶形态的转变,从而提高含Cu锆合金的耐腐蚀性能。 相似文献
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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. 相似文献
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锆合金是目前唯一大规模商用的压水堆燃料包壳材料,其耐水侧腐蚀性能是影响核反应堆安全性与经济性的重要因素。微量合金元素(Fe、Nb等)主要以第二相的形式弥散分布在锆合金基体中,但可对锆合金的腐蚀行为产生显著影响。本文比较了不同锆合金中第二相的差异,综述了锆合金中典型第二相的腐蚀行为及其影响因素。分别比较了二元及三元第二相中主要合金元素Fe和Nb的腐蚀过程,总结了不同水化学条件下第二相腐蚀产物的差异及其对锆合金基体腐蚀行为的影响,并指出当前针对第二相腐蚀行为研究中存在的不足。最后,对锆合金第二相腐蚀行为研究趋势进行了展望,先进微观表征手段可进一步完善含Fe、Nb元素第二相的腐蚀机理研究,将为提高我国新型锆合金包壳材料的耐腐蚀性能提供理论参考。 相似文献
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本文通过试验研究了Zr-Sn-Nb锆合金板材热轧过程中道次变形量和退火温度对锆合金板材微观组织、第二相粒子、力学性能和耐腐蚀性能的影响。试验结果显示:增大热轧道次变形量有细化轧制板材纤维组织的作用,当道次变形量增大到15%时,轧制板材出现裂边;轧制板材采用600℃×50 min退火,其力学性能和耐腐蚀性能都较好,达到核级锆板材使用要求,此样品板材组织细小、均匀,第二相粒子Zr-Nb-Fe大多呈弥散分布晶粒内部,少数位于晶界,且第二相中Nb含量明显较高。 相似文献
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The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60>AM60>AZ31>AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy. 相似文献
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锆合金疖状腐蚀研究综述 总被引:6,自引:0,他引:6
疖状腐蚀是沸水堆中锆合金表面经常发生的1种局部腐蚀现象,它的产生直接影响包壳管的使用寿命和反应堆的安全性,为了全面认识疖状腐蚀的发生、发展及其控制因素,本文总结了国内外疖状腐蚀研究方面的一些主要成果,介绍了疖状蚀斑的形貌、形成机理以及及影响因素。在形成机制方面,目前主要有KUWAE的氢积聚模型和周邦新的形核长大模型。在疗状腐蚀的影响因素方面,认为主要有表面影响、热处理影响、合金成分影响、第二组影响、辐照影响等。最后指出了提高材料抗疗状腐蚀性能的工艺措施:提高Fe Cr含量、降低Sn含量、昼减少淬火后的退火次数和退火温度、降低锆合金制品的表面粗糙可以有效提高锆合金的抗疖状腐蚀能力,最根本的措施还是使用含铌新锆合金。 相似文献
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《腐蚀工程科学与技术》2013,48(2):104-109
Nuclear fuel cladding for pressurised water reactors is commonly manufactured with zirconium alloys. The M5 alloy is a relatively new cladding material for in-reactor used with enhanced performance compared to traditional zircaloys. In this work, the influence of temperature on the corrosion resistance and semiconducting properties of the passive film formed on the M5 alloy in a borate buffer solution has been evaluated. The electrochemical behaviour of the zirconium alloy was assessed by potentiodynamic polarisation tests, electrochemical impedance spectroscopy and Mott–Schottky plots. The results indicated that the corrosion resistance of the M5 alloy decreased with temperature due to the formation of a less stable and more defective passive film. The Mott–Schottky approach used in combination with polarisation tests and impedance measurements was effective to reveal the protective state of the passive film on the M5 alloy. 相似文献
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采用浸泡实验、电化学实验、腐蚀形貌观察以及扫描开尔文探针测试等实验方法对挤压态和退火态二元Mg-xLi(x=1,3,5,质量分数,%)合金的耐腐蚀性能进行研究。结果表明:挤压态Mg-Li合金经350 ℃/4 h退火处理后,可在基体中形成退火孪晶。在 0.1 mol/L NaCl溶液中,退火态合金的耐腐蚀性能明显劣于挤压态合金。通过扫描电子显微镜和激光共聚焦三维形貌分析,发现挤压态合金在腐蚀初期具有丝状腐蚀特征,并且随着腐蚀时间的延长形成了腐蚀坑;退火态合金表面发生快速腐蚀损伤,同时形成较大且深的腐蚀坑形貌。另外,退火态Mg-3Li合金的腐蚀等势线分布表明该合金退火孪晶区域优先发生了腐蚀溶解现象。因此,退火孪晶与母体晶粒之间可形成微电偶腐蚀效应,且退火孪晶区域充当阳极,母体晶粒作为阴极,从而降低了退火态Mg-Li合金的耐腐蚀性能。 相似文献
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Wei-Jia Gong Cong-Feng Wu Hang Tian Xiao-Dong Ni Hai-Long Zhang Xi-Tao Wang 《稀有金属(英文版)》2013,32(5):480-485
Zr-Nb-Cr alloys were used to evaluate the effects of alloying elements Nb and Cr on corrosion behavior of zirconium alloys. The microstructures of both Zr substrates and oxide films formed on zirconium alloys were characterized. Corrosion tests reveal that the corro- sion resistance of ZrxNb0.1Cr (x = 0.2, 0.5, 0.8, 1.1; wt%) alloys is first improved and then decreased with the increase of the Nb content. The best corrosion resistance can be obtained when the Nb concentration in the Zr matrix is nearly at the equilibrium solution, which is closely responsible for the formation of columnar oxide grains with protective characteristics. The Cr addition degrades the corrosion resistance of the Zrl.lNb alloy, which is ascribed to Zr(Cr,Fe,Nb)2 precipitates with a much larger size than β-Nb. 相似文献
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Composite tubes with high corrosion resistance at high temperatures This paper describes studies on the compatibility of alloys used in composite tubes exposed to 600–800 °C. The alloys were chosen on the basis that one (ironrich, clad alloy) has good high temperature strength and the other (nickel-chromium cladding) has good high temperature corrosion resistance. The interdiffusion of elements from one alloy to the other has been studied using the microprobe analyser. The interdiffusion of major alloy elements (e.g. iron) is affected both by the chromium content of the cladding and the zirconium content (added to improve hot workability). The diffusion of carbon from the clad alloy into the cladding is controlled by the identity of the carbide forming elements in the clad material. The mechanism of these compositional effects is discussed. 相似文献