材料期刊网

THEORETICAL PREDICTION OF PROEUTECTOID FERRITIC TRANSFORMATION IN HYPO-PROEUTECTOID STRUCTRAL STEELS

H.B. Chang , Z.G. Li , T. Y. Hsu , Z. Y. Xu , and X. Y. Ruan (Department of Metallurgical Engineering , Shanghai Technical College of Metallurgy , Shanghai 200233 , China)(Department of Plasticity Technology , Shanghai Jiao Tong University , Shanghai 200030 , China)(Department of Materials Science , Shanghai Jiao Tong University , Shanghai 200030 , China)

金属学报(英文版)

Proeutectoid ferrite with carbon content xo precipitating from austenite in a multicomponent steel at temperature T is supposed to be equivalent to proeutectoid ferrite with the same carbon content precipitating from austenite in Fe-C binary system at temperature T'.is described as the temperature difference of proeutectiod ferrite formation, and can be calculated from the Fe-X diagrams and the equilibrium temperature A3. By introducing Tf and basing on the thermodynamic model for Fe-C binary alloy, the driving force for phase transformation from austenite to proeutectoid ferrite in multicomponent steels has been successfully calculated. Through the Johnson-Mehl equation and using the data hem known TTT diagrams, the relationship between the chemical composition and the intedecial edenly packeter as well as activation energy for proeutectoid ferrite formation can be calculated. The starting curves of proeutectoid ferritic transformation calculated in this way in some hypo-proeutectoid structural steels agree well with the erperimental data.

关键词: proeutectoid ferrite formation temperature difference , null , null

THEORETICAL PREDICTION OF THE KINETICS CURVES OF PEARLITIC TRANSFORMATION IN HYPO-PROEUTECTOID STRUCTURAL STEELS

Z.G. Li , H.B. Chang , T. Y. Hsu , Z. Y. Xu , and X. Y. Ruan (Department of Plasticity of Technology , Shanghai Jiao Tong University , Shanghai 200030 , China)(Department of Metallurgical Engineering , Shanghai Technical College of Metallurgy , Shanghai 200233 , China)(Department of Materials Science , Shanghai Jiao Tong University , Shanghai 200030 , China)

金属学报(英文版)

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词: pearlite formation temperature difference , null , null

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

SOFC阴极材料(La_(0.85)Sr_(0.15))_y(Mn_(1-z)Cr_z)O_3的物理性能和化学稳定性

杨威 , 隋智通

材料研究学报

采用烧结法制备阴极材料(La0.85Sr0.15)y(Mn1z-Crz)O3(y=0.85;1;z=0.1,0.2).研究了多孔锰酸镧与致密ZrO2(8mol%Y2O3)界面的成分变化和显微形貌(La0.85Sr0.15)(Mn0.9Cr0.1)O3呈现高电子电导率、良好的热膨胀系数匹配和化学稳定性而(La0.85Sr0.15)MnO3未起到阻止界面退化的作用在1300～1500℃范围内Mn、La、Zr和Sr发生扩散,其中Mn的扩散明显

关键词: SOFC , lathanum manganite. chemical stability , thermal expansion , conductivity , null

新型SOFC阳极材料La0.7Sr0.3Cr0.5-yMn0.5-zCo(y+z)O3的制备和性能表征

何恩全 , 马文会 , 刘荣辉 , 于洁 , 戴永年

稀有金属 doi:10.3969/j.issn.0258-7076.2007.04.019

采用了甘氨酸-硝酸盐法制备了La0.7Sr0.3Cr0.5-yMn0.5-zCo(y+z)O3(y, z=0.1, 0.2)系列阳极材料.借助XRD, SEM对所制备的材料进行了物相和形貌分析.XRD表明利用GNP法制得的粉体在1350 ℃烧结5 h可以形成完整的钙钛矿相;SEM分析可知所得物料颗粒呈球状,尺寸约为1 μm,且没有团聚现象.同时,XRD显示La0.7Sr0.3Cr0.5Mn0.4Co0.1O3和La0.9Sr0.1Ga0.8Mg0.2O3电解质之间具有较好的化学相容性.采用直流四探针法测试了不同组成材料在250～800 ℃温度范围内在空气中的电导率,发现该系列材料在该温度段范围符合小极化子导电机制.另外,利用直流四探针法测试了La0.7Sr0.3Cr0.5Mn0.4Co0.1O3在不同还原气氛下的电导率,在CH4和H2气氛中,La0.7Sr0.3Cr0.5Mn0.4Co0.1O3最大电导率分别达到了4.5和0.42 S·cm-1.

关键词: 钙钛矿 , 阳极 , 电导率

直流磁场对Mg-Y-C u-Z r合金结晶取向和性能的影响?

黄曼青 , 周全 , 刘峰 , 黄金角

材料导报 doi:10.11896/j.issn.1005-023X.2016.22.010

研究了0~1.4 T的直流磁场对陶瓷型铸造 Mg-Y-Cu-Zr 合金结晶取向和力学性能的影响。结果表明直流磁场对合金的初生相没有明显影响，但磁场强度大于1.12 T时，合金第二相的分布变得不连续。当磁场强度小于0.84 T时，α-Mg在(002)面的衍射峰逐渐增强，但变化不明显；当磁场强度大于0.84 T 时，α-Mg 基体在(002)、(101)面的衍射峰强度明显减弱，而在(100)晶面衍射峰强度有所增强。磁场处理后，合金的综合力学性能得到了改善；当磁场强度为1.4 T 时，其抗拉强度和伸长率最高，分别为237 MPa 和8.5%，较无磁场处理时分别提高了38.6%和33.4%。

关键词: 直流磁场 , Mg-Y-Cu-Zr合金 , 结晶取向 , 力学性能

X Y Z particles at BABAR

中国物理C

关键词:

奇Z超重核的禁戒α衰变

许昌 , 任中洲

原子核物理评论 doi:10.11804/NuclPhysRev.30.03.308

采用密度依赖的结团模型研究了奇Z超重核的禁戒α衰变,α粒子与子核之间的微观核势通过双折叠模型对M3Y核子-核子相互作用势以及α粒子与子核的密度积分给出.α粒子与子核之间的库仑相互作用也通过α粒子与子核的电荷密度积分给出.计算发现,由于非零角动量带来的禁戒效应和小的α粒子预形成几率,奇Z超重核的α衰变寿命会明显变长.

关键词: α衰变 , 超重核 , 结团模型

A Hydrogen Sensor Using SrCe_0:95Yb_0:05O_3-α as Proton Conductor and YH_x+Y H_2-z as Reference Electrode for Determining Hydrogen Pressure in Solid Steel

Ying Liy Changzhen Wang Zhongli Zhang Jiangxin Wang

材料科学技术（英文）

The steel contains a small amount of hydrogen which will escape during the heat treatment. The hydrogen pressure in 16MnRE steel was investigated with a hydrogen sensor, which used SrCe_0:95Yb_0:05O_3-α proton conductor as a solid electrolyte, YH_x+YH_2-z as a solid state reference electrode and Ni wire as electrode constructing a hydrogen concentration cell, shown as Ni|_YH_x+YH_2-z |SrCe_0:95Yb_0:05O_3-α |[H]_steel |Ni. The response time of sensor is less than 10 s. The relational expression of hydrogen partial pressure with temperatures was determined using two shape proton conductors. The results showed the regularity in experimental temperature range, and the hydrogen partial pressure increased as its temperature was raised.

关键词: Hydrogen sensor , Proton conductor , Solid electrolyte

稀土Y对镁合金显微组织及腐蚀性能的影响

马宏 , 彭晓东 , 谢卫东

腐蚀学报（英文）

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 , yttrium , microstructure , corrosion resistance