材料期刊网

Effect of Phosphates on the Metal Ion Activated Surface Complexes at the SiO_2-H_2O Interface and in Quartz Deactivation in Flotation System

SUN Zhongxi W. Forsling CHEN Jin Division of Inorganic Chemistry , Lulea University of Technology , S-951 87 Lulea , SwedenDept.of Mineral Engineering , Central South University of Technology , Changsha , 410083 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

The complexation of phosphates in the quartz-metal ion-H_2O-oleate system was studied. Computer assisted calculations with the aid of the advanced program SOLGASWATER and known equilibrium constants were used to evaluate the mechanism,The calculation results revealed that in the presence of a certain amount of phosphates, metal ions adsorbed at the quartz-H_2O interface will be transferred into solution.Thus the competi- tion for metal ions between phosphates and the quartz surface leads to surface deactivation and re- duced floatability.Various distribution diagrams clearly demonstrate the change of surface complexation as a function of added phosphate concentration.The deactivation products were also evaluated.

关键词: complexation , null , null , null , null , null

Protective Characteristics and Formation Mechanism of the Corrosion Product Films of B30 Tubes Exposed to Seawater

ZHU Xiaolong LIN Leyun Surface Technology Center , General Research Institute for Nonferrous Metals , Beijing , 110083 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

The corrosion product films of two kinds of B30 tubes(similar to CDA 715)exposed to seawat- er for various periods of time were investigated by SEM,AES and XPS.The results show that the pro- tective corrosion product film is thin,uniform and adherent.FeOOH is found to be present in the film surface,which confirms the hypothesis that iron hydroxide segregates at the surface of the film.The FeOOH promotes Ni enrichment in the corrosion layer by preventing Ni from running off.The corro- sion product film with no protectiveness is of lay- ered structure,loose and bad adherence.The for- mer film is formed through direct oxidation and the latter by precipitation and redeposition from dis- solved species.

关键词: Cu-Ni alloy , null , null

Mechanical Alloying of Co and Al Powders

CHENG Lizhi ZHANG Yumei SUN Daozhi XIONG Xiangyuan HE Kaiyuan Dept.of Materials Science , Northeast University of Technology , Shenyang , 110006 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

关键词: mechanical alloying , null , null

Isothermal Crystallization Kinetics of an Amorphous CuTi Alloy

MIAO Weifang LI Shuling WANG Jingtang State Key Laboratory for RSA , Institute of Metal Research , Academia Sinica , Shenyang 110015 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

Isothermal crystallization kinetics of Cu_(40)Ti_(60)amorphous alloy has been studied using differential scanning calorimetry(DSC).Both as-quenched and pre-annealed ribbons were inves- tigated.For crystallization of as-quenched amor- phous ribbon in Ar,it was found that the kinetics follows Johnson-Mehl-Avrami equation with mean Avrami exponent n=2.58,which indicates that crystallization of amorphous Cu_(40)Ti_(60)is a three-dimensional diffusion controlled growth pro- cess with constant nucleation rate,i.e.,primary crystallization process.The primary phase is the tetragonal CuTi_2.The as-quenched amorphous ribbons were also crystallized in air,the results re- veal that oxidation has no significant influence on crystallization kinetics of amorphous Cu_(40)Ti_(60). The results of crystallization of pre-annealed rib- bons show a decreasing tendency of Avrami expo- nent with increasing pre-anneal time.The local activation energy and local Avrami exponent dur- ing crystallization process of as-quenched amor- phous alloy were also examined.

关键词: crystallization kinetics , null , null

Miscibility Gap in the Fe-Cu-Ni System at 1173 K

GAN Weiping JIN Zhanpeng Central-South University of Technology , Changsha , 410083 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

The isothermal section of the Fe-Cu-Ni ternary system at 1173 K was determined by microprobe analysis and diffusion triple technique. The experimental results show that this isothermal section only contains a miscibility gap region,and the maximal Ni content in the miscibility gap is 44.7 at.-%Ni.

关键词: Fe-Cu-Ni phase diagram , null , null

Surface Characterization of Ni_(64)P_(20)Fe_(16)Amorphous Alloy by X-ray Photoelectron Spectroscopy and Auger Electron Spectroscopy

By JIANG Honggang WANG Jingtang DING Bingzhe State Key Laboratory for RSA , Institute of Metal Research , Academia Sinica , Shenyang , 110015 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

The nature of the native oxides formed on the surface layer of amorphous alloy Ni_(64)P_(20)Fe_(16)has been studied by X-ray photoelectron spectroscopy (XPS)and Auger electron spectroscopy(AES)with depth profiling by ion bombardment.There are great distinctions in compositions and chemical states between the surface layer and the bulk.The main constituents Ni,P and Fe are lower in the sur- face layer,and they are mostly in oxidized states, whereas C,O and N are enriched in the surface lay- er.The thickness of surface oxide layer is approximately 20 nm,this layer was assumed to be of great significance to various properties of amor- phous alloy Ni_(64)P_(20)Fe_(16),expecially to the chemical and catalytic properties.Experiments proved that transitional element Fe cannot improve oxidation resistance of the amorphous Ni-P system.

关键词: amorphous alloy Ni_(64)P_(20)Fe_(16) , null , null

Temperature and Stress Dependence of Occurrence of Strain Burst in Cyclic Creep of AI-Mg Alloy

ZHU Shijie YANG Zhian WANG Zhongguang State Key Laboratory for Fatigue and Fracture of Materials , Institute of Metal Research , Shenyang , 110015 , ChinaTo whom correspondence should be addressed

材料科学技术（英文）

Cyclic creep tests of Al-Mg alloy have been conducted at a wide range of stress and temperature.When Mg content is beyond 0.45%, the strain bursts can be observed in the cyclic creep curves.There exists a critical stress for the occur- rence of the strain burst,which increases with an in- crease of Mg content and is almost 60% of the ul- timate tensile stress.The occurrence of strain burst is proposed to be controlled by the easiness of the cross-slip of dislocations.For Al-Mg alloy,the dynamic strain aging plays an important role in the strain bursts.

关键词: cyclic creep , null , null , null