S.L. Zheng
,
Y. Zhang
金属学报(英文版)
A new method for chromate cleaning production named chromite caustic fusion pro-cess, is advanced by Institute of Chemical Metallurgy, the Chinese Academy of Sci-ences. With sodium hydroxide as reaction medium, the new process is composed ofthree procedures: liquid phase oxidation of chromite - metastable phase separation -carbonation ammonium transition. Generally illustrating the new process and its fea-tures, this paper mainly studies the thermodynamics of chromite oxidation. The newprocess has much better practical results than the conventional chromate productionprocess in which sodium carbonate is used as reaction medium. The superiority is alsoshown through thermodynamic studies.``
关键词:
chromite
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null
,
null
,
null
,
null
A.Q. Lü
,
Y. Zhang
金属学报(英文版)
By means of surface mechanical attrition treatment (SMAT), the grain size with a diameter of about 60nm formed at about 20μm depth and numerous mechanical twins at about 50μm depth from the treated surface were synthesized in 316L stainless steel because of the different distributions of strain and strain rate along depth orientation. For instance the maximum strain rate reached 103-104s-1 on the top surface. The relationship between the microstructure and the corrosion property was studied in 0.05M H2SO4+ 0.25M Na2SO4 aqueous solution, and the results show an extreme improvement of corrosion resistance owing to the appearance of twin boundaries and the obvious reduction in corrosion resistance attributed to the presence of nanocrystaline boundaries.
KEY WORDS surface mechanical attrition trea
关键词:
surface mechanical attrition treatment
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腐蚀性能
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孪晶界
,
纳米晶界
马宏
,
彭晓东
,
谢卫东
腐蚀科学与防护技术
利用对掺法熔铸镁合金AJ61+xY, 研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为. 结果表明, 添加稀土Y使AJ61镁合金的晶粒明显细化,Mg17Al12 相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al2Y、Al3Y, AJ61镁合金的耐腐蚀性得到明显改善. 耐腐蚀性顺序为:AJ61+1.5%Y>AJ61+2.0%Y>AJ61+1.0%Y>AJ61+0.5%Y.
关键词:
Mg-6Al-1Sr 镁合金
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yttrium
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microstructure
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corrosion resistance
马宏
,
彭晓东
,
谢卫东
腐蚀科学与防护技术
利用对掺法熔铸镁合金AJ61++xY,研究了合金中相的组成和分布及其在3.5%NaCl溶液中的腐蚀行为.结果表明,添加稀土Y使AJ61镁合金的晶粒明显细化,Mg17Al12相的数量明显减少且由连续网状变成弥散颗粒状分布,沿晶界处生成耐蚀稀土相Al2Y、Al3Y,AJ61镁合金的耐腐蚀性得到明显改善.耐腐蚀性顺序为:AJ61+1.5%Y＞AJ61+2.0%Y＞AJ61+1.0%Y＞AJ61+0.5%Y.
关键词:
Mg-6Al-1Sr镁合金
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钇
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显微组织
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耐腐蚀
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）
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:
Transactions of Nonferrous Metals Society of China
The influence of Zr and Y on the cast microstructure of a nickel-based superalloy was investigated by optical microscopy (OM), scanning electron microscopy(SEM), electron probe micro-analysis (EPMA) and X-ray diffraction (XRD). The gamma+gamma' eutectic volume in the superalloy rises notably with the increase of Zr or Y content. Meanwhile, the morphologies of primary MC carbides change from needle and platelet-like to blocky shape with increasing Zr and Y doped. The XRD results show that the primary MC carbide lattice constant increases with Zr and Y additions, and EPMA investigation shows that the platelet-like MC carbides contain primarily Nb and C, while those carbides in blocky shape have 39.2% Zr and 39.6% Nb in average,. These influences on the cast microstructure can be attributed to the atomic size effects of Zr and Y.
关键词:
yttrium;zirconium;carbides;nickel based superalloys;microstructure;solidification;carbide morphology;mechanical-properties;boron;ni3al;yttrium;sulfur
材料科学技术（英）
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
王永刚
,
何业东
,
朱日彰
中国稀土学报
通过金属蒸汽真空弧离子源(简称MEVVA)方法在Fe3Al表面离子注入Y.在1000°空气中的氧化实验表明,Fe3Al经离子注入Y后,初期氧化速率略有升高,但稳态氧化速率大大降低,氧化膜的塑性和粘附性大大提高,抗氧化性能明显改善.其原因在于注入的Y+在氧化过程中优先氧化,阻碍金属离子向外扩散,促进氧向内传输,改变了氧化膜的形成和生长机制.
关键词:
稀土
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钇
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Fe3Al
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离子注入
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高温氧化行为
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
