Y.S. Yang
,
X.H. Feng
,
G.F. Cheng
,
Y.J. Li
,
Z.Q. Hu
金属学报(英文版)
The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al, Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the cellular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ' phase is more uniform and the size of the γ' phase is smaller with the electric field than that without the electric field.
关键词:
single crystal superalloy
,
null
王龙妹
,
杜挺
金属学报
用直接平衡法研究了1500,1550,1600℃Ni液中Y-S平衡关系,测定了钇的脱硫常数lgK_(YS)及Y,S的一阶活度相互作用系数e_S~Y与温度的关系,并进行了有关的热力学计算。由测得的数据算出Ni液中YS的标准生成自由能△G_((Y)S),钇的标准溶解自由能△G_((Y)(l)→[Y]Ni),活度系数γ_Y~o,以及钇的克原子分数自相互作用系数∑_Y~Y和百分浓度自相互作用系数e_Y~Y与温度的关系。 对于反应[Y]_(Ni)+[S]_(Ni)=YS_(s) △G_((Y)S)=-215000+95.53T(cal/mol)脱硫常数: lgK_(YS)=-47000/T+20.86 e_S~Y=-350200/T+179 △G_((Y)(l)→[Y]Ni)=126200-79.31T(cal/mol) lgγ_(Y)=27584/T-15.151 ∑_Y~Y=-127T05/T+69.79 e_Y~Y=-364.8/T+0.2018
关键词:
LI Guodong
,
D U Ting
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China LI Guodong
,
Department No.16
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
100081
,
China
金属学报(英文版)
The thermodynamic properties of Cu-Ce-S and Cu-Y-S liquid solutions were studied by the chemical equilibrium technique at 1200℃. The equilibrium constants and the standard free energies of formation of CeS and YS were determined for the reactions: CeS=[Ce]+[S] and YS = [Y]+[S] . For the solution of Ce_(1) and Y_(l) in pure Cu according to the reactions: Ce_(1)= [Ce] and Y_(1)= [Y] , the standard free energies of solutions were obtained. The first order and second order interaction coefficients between solute elements as well as the activity coefficients γ_(Ce)~0 and γ_Y~0 in liquid Cu were also determined.
关键词:
Cu-Ce-S system
,
null
,
null
王龙妹
,
杜挺
金属学报
由低温无水电解稀土夹杂物和固体电解质定氧活度测得Ni液中钇的脱硫氧常数与温度的关系:lgKr_2o_2s=-(33146)/T+3.85,(1500-1600℃)钇的硫氧化物在Ni液中的标准生成自由能与温度的关系:2[Y]+2[O]+[S]=Y_2O_2S_(s),(1500—1600℃)△G°=151640+17.61T(cal/mol)=-634460+73.69T(J/mol)由实验测得数据经热力学分析计算得到1600℃Ni液中[Y]-[S]-[O]平衡立体图及α_o-α_s平衡相图,为理论上预测夹杂物生成的先后次序及类型提供了依据.并给出了Ni液中加钇控制夹杂物形态公式,钇的加入量与氧,硫含量之间的函数关系.
关键词:
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:
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
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
The bio-corrosion properties of Mg-Zn-Mn alloys with and without Y in Hank's solution at 37 degrees C were investigated by using electrochemical test and electrochemical impedance spectra (EIS). The results of open circuit potential (OCP) and polarization tests indicated that Y could reduce the cathodic current density. A passivative stage appeared in the Tafel curve of the Y containing magnesium alloy, indicating that a passivative film was formed on the surface of the Y containing magnesium alloy. EIS results showed that the Y containing alloy had higher charge transfer resistance and film resistance, but lower double layer capacity than the alloy without the Y element. The surface reaction product identification by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the surface corrosion products were hydroxide and phosphate (Mg(3)Ca(3)(PO(4))(4)) for Mg-Zn-Mn alloy and phosphate (MgNaPO(4)) for the Y containing Mg-Zn-Mn alloys. The XPS results also showed that a Y(2)O(3) protective film was formed on the surface of the Y containing magnesium alloy which contributed mainly to the low cathodic current density and the high resistance. (C) 2009 Elsevier B.V. All rights reserved.
关键词:
Magnesium alloy;Corrosion properties;Y(2)O(3);Electrochemical;impedance spectra;Biomedical materials;quasi-crystalline particles;in-vivo corrosion;magnesium alloys;mechanical-properties;microstructure;phase
欧阳芳平
,
唐波
稀有金属材料与工程
研究了 Y2O2S:Tb纳米晶的发光性质和能量传递过程,根据浓度猝灭曲线分析了纳米 Y2O2S中引起 5D3和 5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用.纳米 Y2O2S中 Tb离子的 5D3-7F5跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短,根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合,得到理论和试验一致的结果.
关键词:
Y2O2S: Tb纳米晶
,
发光性质
,
能量传递过程
王妮燕
,
蒋仕军
,
罗军
,
龚宽
钢铁
在Y45S20易切削钢试制过程中对硫含量、脱氧工艺、钢水温度、连浇温度及速度等关键工艺作了调整和改进,特别是在连铸大批量生产中对各工艺要点的控制以及对各主要成分的分期控制,使Y45S20易切削钢具有合理的成分分布、较好的力学性能和优异的切削性能.
关键词:
连铸
,
脆化敏感温度
,
过热度
,
MnS夹杂
,
易切削性
