材料期刊网

RELATION BETWEEN THE INTERGRANULAR SEGREGATION OF SAND THE HOT DUCTILITY IN HIGH PURITY Fe SALLOYS

C. M. Liu1) , K. Abiko2) and M. Tanino2) 1) Schoolof Materials and Metallurgy , Northeastern University , Shenyang 110006 , China 2) Institute for Materials Research , Tohoku University , Sendai980 , Japan

金属学报(英文版)

Effectoftheintergranularsegregationof Sonthehot ductilityof high purityiron wasquan titativelyinvestigated using high purityiron specimenscontaining < 2 ,5,10 ,20 and 60massppm Sby scanning AES,tensiletests under high vacuum and SEMof the fracturedsurface. The main resultsareasfollows: high purityironcontaininglessthan 2 massppm Sexhibitsanexcellenthotductility,thatis,reductionofareatofracturelargerthan95 % ,at alltesttemperaturesbetween673 and 1173 K. Dissolved Sof5 massppm causesanevident hot ductility dropof high purityiron at873～973 K.Increasingthedissolved Scontentfur ther decreases hot ductility and widensthetemperaturerange ofembrittlement. Theembrit tledspecimensfailinintergranular mode. Theamountoftheequilibrium intergranularseg regation of Sincreases withincreasingtheconcentration of dissolved Sand with decreasingthe annealingtemperature. Ssegregates much moreon cavitysurfacesthan atgrain boundaries.

关键词: high purityiron , null , null , null , null , null

PREVENTION OF THE INTERGRANULAR FRACTURE AT ELEVATED TEMPERATURES BY ADDITION OF PHOSPHORUS TO A HIGH PURITY Fe0 002% SALLOY

C. M. Liu1) , K. Abiko2) and M. Tanino2) 1) Schoolof Materials and Metallurgy , Northeastern University , Shenyang 110006 , China 2) Institute for Materials Research , Tohoku University , Sendai980 8579 , Japan

金属学报(英文版)

Theeffectof phosphorusonthehotductility andthesegregation ofsulfuratgrain boundariesin high purityironcontaining 0 002 % sulfur werequantitativelyinvestigated bytensiletestat973 K, SEMobservation of fracture surface and scanning Auger electron spectroscopy.Theexperimental resultscan besum marized as follows:(1) addition of phosphorustothe iron remarkablysuppressestheintergranular fractureinduced bythesegregation of sulfur at973 Kandincreasesthe hot ductility;(2) phosphorusstrikingly decreasesthesegregation ofsulfur atgrain boundaries, whichisresponsibleforthesuppressionoftheintergranularfrac tureat973 K;(3) theremarkably decreasedsegregation ofsulfur atgrain boundariesbytheaddition of phosphoruscan beexplained bythesitecompetitioneffectandtherepulsiveinter action at grain boundariesbetweensulfuratomsand phosphorusatoms;(4) sulfurstrikinglysegregatestothevoid surfacesformed on grain boundaries, while phosphorushaslittlesegre gationtothevoid surfaces.

关键词: high purity iron , null , null , null

Thermoelectric Characterization of (Na1-yMy)1.6Co2O4 (M=K, Ca, Sr)

Ying LI

材料科学技术（英）

Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Power-factor of Na Co2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W•m-1•K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W•m-1•K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.

关键词: Thermoelectric materials , materials , Electric , proper

M_1-M_2-x-y系优势区相图的绘制及其应用

王龙章 , 黄克雄 , 骆如铁 , 姚渝 , 叶大陆 , 陈新民

金属学报

本文讨论了双金属共存体系M_1-M_2-x-y,当两种金属的化合物相互作用生成多金属化合物时,优势区相图的绘制原理、方法及计算机程序。通过绘制Zn-Fe-SO系的优势区相图,分析了ZnO·Fe_2O_3的生成及稳定条件,并说明了其在硫化锌矿焙烧中的指导作用。

关键词: M_1-M_2-x-y体系 , predominance diagram , roasting , zinc sulfide ore

ZrO2 strengthened NiAl/Cr(Mo,Hf) composite fabricated by powder metallurgy

自然科学进展﹒国际材料（英文）

The ZrO2 ceramic particles strengthened NiAl/Cr(Mo,Hf) composite was fabricated from the rapidly solidified NiAl/Cr(Mo,Hf) pre-alloyed powder and the ZrO2 powder by powder metallurgy technique. Microstructure examination revealed that in the prepared composite NiAl and Cr(Mo) phases distributed at the eutectic cell boundary become coarse but many Cr(Mo) platelets inside the eutectic cell were broken, which was different from the original powder. Moreover, fine Ni2AlHf and Hf solid solution particles distributed uniformly in the composite, and the ZrO2 particles mainly segregated along eutectic cell boundary. In addition, twin crystal and stacking faults were observed inside of ZrO2 grains. The experimental results showed that the ZrO2 ceramic particles strengthened NiAl/Cr(Mo,Hf) composite exhibited better room temperature and high temperature mechanical properties than the NiAl/Cr(Mo,Hf) alloy, which may be attributed to the fine structure and the strengthening effect of ZrO2 particles. (C) 2012. Chinese Materials Research Society. Production and hosting by Elsevier Ltd. All rights reserved.

关键词: NiAl intermetallics;NiAl/Cr(Mo) composite;Powder metallurgy;ZrO2;strengthening;temperature compressive properties;mechanical-properties;eutectic;alloy;microstructure;behavior;nial-cr(mo)-hf

DRAWING PREDOMINANCE DIAGRAM OF M_1—M_2—x—y SYSTEM AND ITS APPLICATION

WANG Longzhang HUANG Kexiong LUO Rutie YAO Yu YE Dalu CHEN Xinmin Central South University of Technology , Changsha , China

金属学报(英文版)

Discussions were made of the principle,method and computer program for drawing the pre- dominance diagrams of the bi-metal co-existed system M_1-M_2-x-y in which the multi-me- tallic compounds may be produced by interaction between compounds of both metals.The formation of zinc ferrite and its stable region have been analyzed through drawing Zn-Fe-S-O system predominance diagrams.The availability of the diagram is given the di- rection to roast the zinc sulfide ore as well.

关键词: system M_1-M_2-x-y , null , null , null

Single crystal T(0.3)MoO(3) growth by electrolytic reduction method of a T1(2)CO(3)-MoO(3) melts

Journal of Crystal Growth

Single crystals of quasi-one-dimensional charge-density-wave conductor blue bronze Tl(0.3)MoO(3) have been grown by electrolytic reduction method using the raw materials Tl(2)CO(3)-MoO(3) with composition around 1:4.3 mol ration. The electrolytic temperature was about 570 degrees C, and electrolytic current was 25 mA during the electrolytic process. By this method, the Tl(0.3)MoO(3) single crystals obtained have a relatively large average size and high quality. Platelet crystals with typical dimensions of 7 x 2 x 1 mm(3) were obtained. The crystal structure is monoclinic with space group C2/m. The parameters of the unit cell of the single crystal are as follows: a = 18.486(6)angstrom, b = 7.555(2)angstrom, c = 10.032(3)angstrom and beta = 118.38(3)degrees. The C-center symmetry of Tl(0.3)MoO(3) crystal is demonstrated by the selected area electron diffraction (SAED) patterns in the transmission electron microscope (TEM). The full-width at half-maximum (FWHM) of the rocking curve of the (201) Bragg peak of the Tl(0.3)MoO(3) was approximately 0.4 degrees. These are evidences that the single crystal is of high quality. The temperature dependence of the resistivity shows that a metal-semiconductor transition occurs near 181 K. (c) 2005 Elsevier B.V. All rights reserved.

关键词: electrolytic reduction;single crystal growth;thallium blue bronze;Tl(0).(3)MoO(3);charge density wave;charge-density-wave;molybdenum oxide bronzes;blue bronze;nonlinear;transport;k0.3moo3;k0.30moo3;memory;dynamics;lithium;noise

Theoretical study of local lattice structure of Mn2+ in perovskite fluorides A(2)MF(4) (A = K, Rb; M = Mg, Zn, Cd) series

Journal of Physics and Chemistry of Solids

A theoretical method for investigating the inter-relation between the molecular structure and electronic structure has been established on the basis of the 252 x 252 complete energy matrices for a 3d(5) configuration ion in a tetragonal ligand field. By means of this method, which is independent of the X-ray diffraction, the local structure of the paramagnetic Mn2+ ion in perovskite fluorides A(2)MF(4) (A = K, Rb; M = Zn, Me. Cd) are determined directly by analyzing the EPR spectrum of octahedral Mn2+ center in A(2)MF(4) crystals and the optical absorption spectrum of the (MnF6)(4-) cluster. It is shown that, comparing with the octahedral cubic structure, the local microstructure in the vicinity of Mn2+ displays an elongated distortion when b(2)(0) > 0 and a compressed distortion when b(2)(0) < 0, and Delta R vs. 10(4)b(2)(0) as well as Delta R vs. 10(4)b(4)(0) in the distortion region is, respectively, approximately linear. Simultaneously, the theoretical zero-field-splitting parameters b(2)(0), b(4)(0) and b(4)(4) are in good agreement with the experimental values. (c) 2006 Elsevier Ltd. All rights reserved.

关键词: crystal fields;crystal structure;electronic structure;zero-field splittings;crystals;ions;spectroscopy;luminescence;resonance;epr

HIGH-FIELD MAGNETIZATION OF YBA2CU3-XMXO7 (M=PB, SN) AT 4.2 K

Journal of Alloys and Compounds

Magnetization measurements on lead- or tin-doped YBa2Cu3O7 have been performed at 4.2 K in magnetic fields up to 29 T. The critical current densities are deduced from the irreversible magnetization and the pinning forces are evaluated. The effect of both lead and tin doping on the critical current density is quite appreciable. In particular, the critical current density of the sample doped with lead is more than twice that of the undoped sample. This effect is thought to be associated with the enhancement of the intergranular coupling of grains through the formation of BaPbO3 phase at the interface of the 123 superconducting phase. The relationship between the critical current density and a micrograph of the tin-doped sample is also discussed.

关键词: transport critical current;y1ba2cu3ox

A novel electrodeposited Cu-Zn-Bi film with increased corrosion resistance in a 0.05 M K(2)SO(4) solution

Applied Surface Science

A single phase Cu-Zn-Bi film is fabricated on the steel wire by electrodeposition. Bi addition (similar to 1 wt.%) greatly increases the corrosion resistance of brass (Cu-36 wt.% Zn) film in a 0.05 M K(2)SO(4) solution as shown by potentiodynamic polarization and electrochemical impendence spectroscopy (EIS) experiments. It is proposed that the main reason for the improvement in the corrosion resistance by the Bi addition is that it greatly increased the crack resistance, which thus prevents crack-induced galvanic corrosion occurring between the brass film and the steel substrate. (C) 2011 Elsevier B. V. All rights reserved.

关键词: Bi;Brass;Electrodeposition;Crack;Corrosion;copper-zinc alloys;coating deterioration;computer-simulations;unleaded brasses;stacking-faults;electrolytes;temperature;bismuth;eis