材料期刊网

PROBABILISTIC MODELING OF BRITTLE FRACTURE WITH PRIOR DUCTILE CRACK EXTENSION

H. Y. Jing , L. X. Huo , Y. F. Zhang and F. Minami( 1) College of Material Science , Tianjin University , Tianjin 300072 , China 2) Osaka University , Japan)

金属学报(英文版)

A computation framework for brittle fracture which incorporates weakest link statistics and a microme- chanics model reflecting reflecting local damage of the material is described.The Weibull stress W emerges as a probabilistic fracture parameter to define the condition leading material failure. Unstable crack propa- gation occurs at a critical value of W which may be attained paior to or following some amount of duc- tile crack extension. A realistic model of ductile crack growth using the computation cell methodology is used to define the evolution of near tip stress fields during crack extension. An application of proposed framework to predict the measured geometry and ductile tearing effects on the statistical distributio of fracture toughness for the pipe line steel welded joint is described.

关键词: fracture toughness , null , null

Corrosion of Y, Fe and Fe-15Y in H_2-H_2S Mixture under 10~(-3) Pa S_2 at 600～800℃

Yan NIU , Weitao WU and Chaoliu ZENG (State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)F. Gesmundo and F. Viani (Instituto di Chimica , Facolta di Ingegneria , Un

材料科学技术（英文）

The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe

关键词:

Corrosion of Y, Fe and Fe-15Y in H-2-H2S mixture under 10(-3) Pa S-2 at 600 similar to 800 degrees C

材料科学技术（英文）

The corrosion of an Fe-based alloy containing 15 wt pet Y in H-2-H2S mixtures under 10(-3) Pa S-2 was studied at 600 similar to 800 degrees C in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneficial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus, Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition, but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12 similar to 17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe.

关键词: high-temperature sulfidation;most-reactive component;ni-nb alloys;h2-h2s mixtures;behavior;600-degrees-c-800-degrees-c;oxidation

Improving glass-forming ability of Mg-Cu-Y via substitutional alloying: Effects of Ag versus Ni

Journal of Materials Research

Based on the best bulk metallic glass (BMG) forming alloy in the Mg-Cu-Y ternary system, we introduced Ag (or Ni) to partially substitute for Cu to improve the glass-forming ability (GFA). The objective of this paper is twofold. First, we illustrate in detail a recently developed search strategy, which was proposed but only briefly outlined in our previous publication [H. Ma, L.L. Shi, J. Xu, Y. Li, and E. Ma: Discovering inch-diameter metallic glasses in three-dimensional composition space. Appl. Phys. Lett. 87, 181915 (2005)]. The protocol to navigate in three-dimensional composition space to land large BMGs is spelled out step-by-step using the pseudo-ternary Mg-(Cu,Ag)-Y as the model system. Second, our ability to locate the best BMG former in the composition tetrahedron allows us to systematically examine, and conclude on, the effects of a given alloying element. The large improvement in glass-forming ability in the Mg-(Cu,Ag)-Y system relative to the based ternary will be contrasted with the reduced glass-forming ability in the Mg-(Cu,Ni)-Y pseudo ternary system. It is demonstrated that the improvement of glass-forming ability requires judicious choice of substitutional alloying elements and concentrations, rather than simple additions of multiple elements assuming the "confusion principle."

关键词: bulk metallic-glass;shaped copper mold;amorphous-alloys;thermal-stability;ternary-system;casting method;p system;diameter;zr;mm

SULFIDATION OF Co-15wt%Y ALLOY IN H_2-H_2S MIXTURES AT 600-800℃

NIU Yan , F.GESMUNDO , WU Weitao , ZENG Chaoliu , F.VIANI , (State Key Laboratory for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang.110015 , China)(Istituto di Chimica , Facolta'di Ingegneria , Universita'di Genova , Fiera del Mare , Pad.D , 16129 Genova , Italy)Manuscript received 3 July 1995

金属学报(英文版)

The corrosion properties of a Co-15wt% Y alloy were studied in H_2-H_2S mixtures under a sulfur pressure of 10-3 Pa at 600-800℃ and of 10-2 Pa at 800℃ to examine the effect of Y on the resistance of pure cobalt to sulfur attack at high temperatures.The alloy is nearly single-phase.containing mostly the intermetallic compound Co17Y2 plus a little amount of the solid solution of Y in cobalt.At 600-700℃ and at 800℃ under 10-2 Pa of S2 the alloy forms multi-layered scales consisting of an outer region of pure cobalt sulfide,an intermediate region of a mixture of the sulfides of the two metals and finally an innermost layer of a mixture of yttrium sulfide with metal cobalt.At 800℃ under 10-3Pa of S2,below the dissociation pressure of cobalt sulfide, the alloy forms only a single layer composed of a mixture of metallic cobalt with yttrium sulfide.Pure Y produces only the oxysulfide Y2O2S, as a result of the good stability of this compound and of the presence of some impurities in the gas mixtures used The corrosion kinetics is generally rather complex and irregular except al 800℃under 10-3 Pa of S2.The addition of yttrium always reduces the sulfidation rate of cobalt, even though the formation of a continuous protective external layer of yttrium sulfide is never achieved.The internal sulfidation of Y in Co-15% Y is not associated with a depletion of Y in the alloy.This kind of diffusionless internal attack is typical of alloys with a very small solubility of the most reactive component Y in the base metal A.which restricts severely the Y flux from the alloy towards the alloy-scale interface.

关键词: :cobalt-yttrium alloy , null , null

H2O和Y(O)对NiCoCrAl热障涂层高温氧化的影响

王逸群 , 宋鹏 , 季强 , 廖红星 , 陆建生

材料工程 doi:10.11868/j.issn.1001-4381.2015.000379

分别利用真空等离子沉积和超音速火焰喷涂技术制备含有Y和含Y氧化物的NiCoCrAl涂层,用差热分析和光学及电子显微镜研究两种涂层在Ar-16.7%O2,Ar-3.3%H2O和Ar-0.2%H2-0.9%H2O气氛中1100℃时的氧化动力学和断面微观结构,通过第一性原理计算对比在不同气氛中含Y氧化物对涂层氧化的影响机理.结果表明:对于NiCoCrAl+Y涂层,Y倾向于向界面扩散并在界面富集导致Al2O3膜生成更多有利于内氧化的孔洞,水蒸气更会对内氧化产生促进作用.而对于NiCoCrAl+Y(O)涂层,由于Y在涂层制备过程中被氧钉扎,导致NiCoCrAl+Y(O)涂层在上述气氛中生成了平直而均匀的Al2O3层,不同气氛对其氧化行为影响较小.上述研究进一步揭示NiCoCrAl涂层中活性元素Y的存在状态和氧化气氛中的水蒸气对氧化铝组织结构和生长速率有重要影响.

关键词: 含钇氧化物 , 水蒸气 , NiCoCrAl涂层 , 热障涂层 , 内氧化

Fe-Y合金在600～800℃H_2-CO_2-H_2S中的腐蚀

牛焱 , 晏人芸

腐蚀学报（英文）

研究了纯Fe、纯Y、Fe-15Y和Fe-30Y合金在600～800℃高硫压(10-3Pa)-低氧压(10-19Pa于600℃或10-15Pa于700℃和800℃)混合气中的腐蚀行为.Y在600℃和700℃发生加速腐蚀,但在800℃形成的腐蚀膜有保护性.加入Y能够降低合金的腐蚀速率,但在所有条件下,合金都形成FeS最外层膜、由两金属的化合物组成的中间层和由α-Fe和Y的硫氧化物的细微混合物所组成内硫化-氧化区.Fe似以相当高的速率穿过中间层形成FeS外层.在合金/氧化膜界面内侧不产生Y的贫化现象.从Y在Fe

关键词: Fe-Y合金 , yttrium , sulfidation , oxidation

反应气体H2O对Y2O3隔离层外延生长的影响

张华 , 金薇 , 刘慧舟 , 杨坚

低温物理学报 doi:10.3969/j.issn.1000-3258.2008.04.009

报道了用反应溅射的方法在有强立方织构的NiW基带上连续制备Y2O3隔离层的研究结果.用X射线θ～2θ扫描,ψ扫描对薄膜的取向和织构进行表征,用扫描电子显微镜(SEM)和原子力显微镜(AFM)对薄膜的表面形貌进行观察.论文主要研究了H2O分压对Y2O3隔离层外延生长以及表面形貌的影响,结果表明:H2O分压过小,Y2O3织构相对衬底有所弱化,薄膜表面不透明,原子覆盖不均匀,且不利于后续隔离层YSZ的生长.同时,临界H2O分压与温度和总气压的关系也作了详细研究.

关键词: 反应溅射 , Y2O3隔离层 , H2O分压 , 表面形貌

新型电荷转移配合物(C9H8N)10(NH4)3[Y(SiMo11O39)2]·20H2O的合成与表征

王世铭 , 黄金凤 , 林深 , 郑瑛

稀土 doi:10.3969/j.issn.1004-0277.2002.01.003

由三元杂多化合物(NH4)13[Y(SiMo11O39)2]·36H2O与喹啉反应合成了电荷转移化合物(C9H8N)10(NH4)3[Y(SiMo11O39)2]*20H2O.采用元素分析、X射线粉末衍射、红外光谱、固体漫反射电子光谱进行了表征.结果表明:喹啉通过N原子结合质子形成阳离子与稀土杂多阴离子成盐,固体化合物中阴离子和阳离子之间存在较强的相互作用;化合物在光激发下发生分子内电荷转移,导致有机C9H8N+大阳离子的氧化和稀土杂多阴离子的还原,标题化合物颜色由黄转变为深蓝色.

关键词: 电荷转移配合物 , 钇 , 多金属氧酸盐 , 合成 , 表征

Role of Y4Al2O9 in High Temperature Oxidation Resistance of NiCoCrAlY-ZrO2•Y2O3 Coatings

Shuqin YANG

材料科学技术（英文）

NiCoCrAlY-ZrO2•Y2O3 coatings were deposited on the substrates by using a technology of combining electron, atom and ion beams (three beams). Isothermal oxidation for these samples was performed at 1100℃ for 100–300 h. The results show that a thermally grown oxide (TGO) layer was formed between NiCoCrAlY layer and ZrO2•Y2O3 layers according to the cross-section morphologies of the samples after high temperature isothermal oxidation. The TGO contains α-Al2O3 and Y4Al2O9 etc. oxides. The intensity ratio of α-Al2O3/Y4Al2O9 was monotonously decreased with increasing oxidation time based on XRD (X-ray diffraction) analysis. The Y4Al2O9 phase plays the most important role in high temperature oxidation resistance at 1100℃. The related mechanism was also discussed.

关键词: NiCoCrAlY-ZrO2·Y2O3 coatings , coatings , XRD , Al2Y4O