Zr-XSn-1Nb-0.3Fe(X=0~1.5)合金的腐蚀行为研究

通过高压釜腐蚀实验研究了Zr-XSn-1Nb-0.3Fe合金(X=0~1.5,质量分数,%)在360℃/18.6 MPa纯水、360℃/18.6 MPa/0.01 mol·L-1 LiOH水溶液以及400℃/10.3 MPa过热蒸汽中的耐腐蚀性能。结果表明,随着Sn含量从1.5%降低至0.6%,合金试样腐蚀增重降低;进一步降低Sn含量时,合金在纯水和蒸汽中的腐蚀增重没有明显变化,但在LiOH水溶液中的腐蚀增重反而增加。采用透射电镜表征腐蚀前的显微组织发现,随着Sn含量的变化,合金中第二相的大小及类型相接近,但面密度随着Sn含量的增加而减少。采用激光拉曼光谱分析腐蚀过程中氧化膜晶体结构表明,腐蚀初期氧化膜的结构以m-ZrO2和t-ZrO2为主,随着腐蚀时间的增加,t-ZrO2转变为m-ZrO2;t-ZrO2转变越快,t-ZrO2含量越低,腐蚀速率越高。     

不同介质对Zr-4合金氧化膜结构的影响

为了解释锆合金在LiOH水溶液中耐腐蚀性能降低的原因，将3组粉状Zr-4合金样品分别放在500℃空气中、500℃过热蒸汽中和350℃的0．1mol／L LiOH水溶液中进行腐蚀，当氧化膜厚度约为1．5gm时，用XRD分析这3组样品的晶体结构。将一片状Zr-4合金样品在350℃的0．04mol／L LiOH水溶液中腐蚀2d，用SIMS检测Li^ 和OH^-在氧化膜剖面上的分布。根据实验结果提出OH^-在氧化膜中比O^-2扩散速度快，使t—ZrO2加速向m-ZrO2转变，导致Zr-4合金腐蚀速度加快。     

纳米化组织处理对锆合金氧化过程中ZrO2晶格常数变化的影响

研究了纳米结构锆合金氧化过程中ZrO2晶格常数的变化.结果表明,氧化过程中,纳米组织合金基底上形成的ZrO2晶格常数变化与普通粗晶基底上形成的ZrO2晶格常数变化有显著不同.纳米组织合金基底上形成的t-ZrO2,晶胞体积在氧化过程中不断缩小,由t-ZrO2转变形成的m-ZrO2晶胞体积也在不断减小;而普通粗晶基底上形成的t-ZrO2晶胞体积减小时,转变形成的m-ZrO2晶胞体积却在不断膨胀.对此并进行了分析讨论.     

Sn含量对N36锆合金在LiOH水溶液中耐腐蚀性能的影响

比较了N36(Zr-1Sn-1Nb-0.3Fe)及低锡N36(Zr-0.8Sn-1Nb-0.3Fe)锆合金样品在360℃/18.6 MPa/0.03 mol/LLiOH水溶液中的耐腐蚀性能,发现N36提前发生腐蚀转折,转折后腐蚀增重远高于低锡N36。观察了腐蚀转折后合金样品氧化膜形貌及物相特征,发现在氧化膜断面上形成平行于氧化膜/金属界面的裂纹,而界面氧化膜呈"菜花"状生长;与N36相比,低锡N36氧化膜形貌显示断面裂纹相对较少,界面生长的氧化膜较为平整;随腐蚀速率的增加,断面裂纹增多,界面膜呈"菜花"状凸起越严重;氧化膜中产生的裂纹与四方相的转变有关。讨论了Sn对N36合金耐腐蚀性能影响的机理,认为固溶在α-Zr中的Sn含量是引起耐腐蚀性能差别的主要原因。     

Zr-0.39Sn-0.32Nb合金微弧氧化膜变温介电性能研究

目的 研究锆合金微弧氧化膜的介电性能随温度的变化规律,了解?100～250℃范围内它们的介电频谱特性.方法 采用恒压模式的双极性微弧氧化脉冲电源,在硅酸盐电解液中对Zr-0.39Sn-0.32Nb合金进行微弧氧化处理,用扫描电子显微镜(SEM)、X射线衍射仪(XRD)及激光拉曼光谱仪(Raman),分析微弧氧化陶瓷膜的形貌和相组成.采用变温介电谱仪测量?100～250℃范围内不同厚度微弧氧化膜的介电常数、介电损耗以及电导率随环境温度变化的频谱图(0.01 Hz～1 MHz).结果 Zr-0.39Sn-0.32Nb合金表面制备出20～45μm厚的微弧氧化陶瓷膜,它们都由m-ZrO2单斜相和少量t-ZrO2四方相组成.微弧氧化膜的致密内层对其介电特性影响较大,多孔外层降低其绝缘性能.在?100～250℃范围内,微弧氧化膜的低频区介电常数、介电损耗、电导率均随着温度的增加而快速增加,而温度对它们在高频区的影响较小.同时,在0～100℃范围内,锆合金微弧氧化膜介电性能稳定.在50 Hz工频和20℃环境中,微弧氧化膜的导电率约为10?12 S/m.结论 环境温度对锆合金微弧氧化陶瓷膜介电特性有较大影响,特别在低频区变化显著.     

Cr对Zr-0.3Nb合金显微组织及在400 ℃/10.3 MPa过热蒸汽中腐蚀行为的影响

通过制备Zr-0.3Nb-xCr(x=0.2, 0.5, 1.0,%,质量分数)合金,并在高压釜中进行400℃/10.3 MPa过热蒸汽腐蚀实验,利用SEM和TEM表征和分析合金基体及氧化膜截面显微组织,研究了Cr对Zr-0.3Nb合金显微组织及在400℃/10.3MPa过热蒸汽中腐蚀行为的影响。结果表明,Zr-0.3Nb-xCr合金中的第二相主要为面心立方和密排六方的ZrCr₂相,尺寸在10～100 nm范围内,随Cr含量增加,第二相的数量增加,但尺寸无明显变化。添加适量的Cr能促进氧化膜中柱状晶的生长并延缓柱状晶向等轴晶的转变,从而改善Zr-0.3Nb合金的耐腐蚀性能。当Zr-0.3Nb合金中添加0.5%的Cr时,耐腐蚀性能较好,这可能是因为Zr-0.3Nb-0.5Cr合金的氧化膜较为致密,且在氧化膜/基体界面处存在亚氧化层,可以延缓氧化膜的显微组织演化,提高合金的耐腐蚀性能。     

水化学及合金成分对锆合金腐蚀时氧化膜显微组织演化的影响

将Zr-4和成分接近ZIRLO的3#合金样品置于高压釜中,经过360℃,18.6 MPa的0.01 mol/L LiOH水溶液腐蚀1 50 d后,增重分别达到310 mg/dm^2和82 mg/dm^2,3#合金的耐腐蚀性能明显优于Zr-4.用透射电镜、扫描电镜和扫描探针显微镜研究了两种样品经过70 d和150 d腐蚀后,氧化膜不同深度处的显微组织和晶体结构;研究了氧化膜的断口形貌和氧化膜的表面形貌.结果表明：Zr-4氧化膜中的空位比3#合金氧化膜中的更容易通过扩散凝聚形成孔洞簇和晶界微裂纹,也容易发展成平行于氧化膜/金属界面的裂纹,导致腐蚀转折提早发生,这与Li^＋和OH^-渗入氧化膜后降低氧化锆表面自由能的程度有关.从氧化膜表面晶粒形貌判断,Zr-4样品形成氧化锆后的表面自由能比3#合金样品形成氧化锆后的低,这是合金成分不同引起的一种差异,也可能是Zr-4样品在LiOH水溶液中的耐腐蚀性能比3#样品差的一个重要原因.     

氧化膜结构及内应力对新锆合金腐蚀机理的影响

采用XRD和Raman光谱技术对NZ2锆合金在360℃,18.6 MPa含锂水和400℃,10.3 MPa蒸汽中腐蚀不同时间后氧化膜的内应力及晶体结构进行测试,通过SEM对氧化膜的显微结构进行表征.结果表明,随着腐蚀时间的延长,NZ2合金氧化膜中四方相含量不断降低,单斜相含量不断升高,发生四方相向单斜相转变.当氧化膜厚度达到2 mm时,出现了立方相.氧化膜中四方相含量越高,锆合金的耐腐蚀性能越好.氧化膜内应力及显微结构的研究结果表明,NZ2合金氧化膜内有高的压应力存在.氧化开始阶段,随着腐蚀过程的进行,氧化膜内部压应力增加.当氧化膜厚度达到2 mm时,氧化膜中压应力超过临界值,氧化膜发生破裂,应力释放发生.裂纹降低了氧化膜的保护性,腐蚀转折发生.转折后氧化膜内压应力很低,而且基本保持恒定.因此,腐蚀转折与氧化膜内压应力的突然释放密切相关.氧化膜中压应力越高,四方相越稳定,耐腐蚀性能越好.同时,探索了氧化膜中四方相和立方相的稳定机理,建立了新锆合金的腐蚀机理模型.     

预渗氢对Zr-4合金在360℃/LiOH水溶液中耐腐蚀性能的影响

核反应堆运行时,锆合金包壳的腐蚀和吸氢相伴发生,被锆合金吸收的氢不但会影响锆合金的力学性能,同时对锆合金的耐腐蚀性能也会产生一定的影响,其影响程度与合金成分和腐蚀条件密切相关。氢对Zr-4合金(Zr-1.3Sn-0.2Fe-0.1Cr,质量分数,%)在LiOH水溶液中的耐腐蚀性能影响机理尚不完全清楚。本工作开展了预渗氢对Zr-4合金在LiOH水溶液中耐腐蚀性能影响规律及其机理的研究。采用气相渗氢法或电解渗氢法对Zr-4合金样品进行渗氢,制备了低氢(20~120μg/g)和高氢(120~250μg/g)样品。将渗氢和未渗氢的样品同时放入高压釜中进行360℃/18.6MPa/0.01mol/LLiOH水溶液的腐蚀试验。采用高分辨扫描电子显微镜(HRSEM)观察氧化膜断口、内表面和外表面形貌;用卷曲法测量氧化膜内应力;采用二次离子质谱仪(SIMS)测定Zr-4样品氧化膜中Li+浓度沿深度方向的分布。研究结果表明:3种氢含量样品在LiOH水溶液中腐蚀时均发生明显的腐蚀转折,但样品中的氢含量越高,转折后的腐蚀速率越小,即耐腐蚀性能越好。与未渗氢样品相比,渗氢样品的氧化膜更加致密,氧化膜/金属(O/M)界面的起伏程度更小,氧化膜显微组织的演化更慢。渗氢样品氧化膜中的应力水平较低,且随氧化膜厚度增加应力下降的趋势更平缓,同时氧化膜中的Li+浓度更低,且沿氧化膜深度方向上Li+浓度下降得更快。这说明合金中的氢可抑制Li+在氧化膜中的扩散、降低氧化膜中的应力水平,延缓氧化膜中空位扩散凝聚形成孔隙、孔隙连通发展成为微裂纹的过程,从而提高了Zr-4合金的耐腐蚀性能。     

Cu对Zr-1Sn-0.35Fe-0.15Cr-0.10Nb合金在400℃含氧过热蒸气中耐腐蚀性能的影响

为了探究Cu对Zr-1Sn-0.35Fe-0.15Cr-0.10Nb(质量分数,%)合金在400℃/1×10^-6μL/L含氧过热蒸气中耐腐蚀性能的影响。将Zr-1Sn-0.35Fe-0.15Cr-0.10Nb和Zr-1Sn-0.35Fe-0.15Cr-0.10Nb-0.05Cu合金样品放入动态高压釜中进行400℃/10.3 MPa/1×10^-6μL/L含氧过热蒸气腐蚀试验。采用SEM、TEM和XPS等表征手段对氧化膜的显微组织以及氧化膜中各元素的价态进行分析。结果表明：微量Cu的添加改善了Zr-1Sn-0.35Fe-0.15Cr-0.10Nb合金的耐腐蚀性能;Cu在氧化膜中主要以Cu和Cu⁺形式存在;Cu的添加会促进氧化膜中的Sn和Sn²⁺向Sn⁴⁺和Fe²⁺向Fe³⁺的转化。从Cu的添加影响氧化膜中合金元素的氧化行为和抑制了氧化膜中孔隙和裂纹生成等角度探讨了Cu改善Zr-1Sn-0.35Fe-0.15Cr-0.10Nb合金耐腐蚀性能...     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

FORMULAS OF TENSION OF CONTINUOUS ROLLING PROCESS

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.     

Bulletin of the Awards in 2013

<正>Five reviewers and 9 published articles are selected as the Excellent Rewewerand Excellent Article in 2013 respectively.Excellent Reviewers:Prof.Z ongyi Ma(Institute of Metal Research,CAS,C hina);Prof.Y ongbo Xu(Institute of Metal Research,CAS,C hina);Prof.Guangping Zhang(Institute of Metal Research,C AS,C hina);Prof.Z hendui Cui(Tianjin University,China);