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The synthesis and magnetic properties of Pr xCe 1 x Fe 2 have been investigated. The forma tion of Pr xCe 1 x Fe 2 is found to depend strongly on annealing temperature. Pure single phase compound can be synthesized at ambient pressure when x≤0 5. The main phase of the Laves structure can still be observed up to x=0 8. Magnetostriction increases with in creasing x and a largest saturation magnetostriction 200 ppm is observed for x=0.5.

关键词: magnetostriction , null , null

STRUCTURE AND BINDING STATE OF CN x FILMS SYNTHESIZED BY FACING TARGETS SPUTTERING

D.Q.Tang , Y. Wang , E.Y.Jiang , C.Zhao and F.L.Sun Department of Applied Physics , Tianjin University , Tianjin 300072 , China

CN x films were made by a facing targets sputtering ( FTS) systemon the  Si(100) substrate under different  N 2 partial pressure.  XRD, XPS, FTIR and Raman Spectroscopy( RS) were measured to investigate the structure and the binding state of the film. The films are amorphous and the  N/C increases with the  N 2 partial pressure increasing and reaches 0 46 when the  N 2 pressure is 100%. The N incorporated  C forms N sp 2C and N sp 3C mainly and there is a small amount of  C≡N.

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PROBABILISTIC MODELING OF BRITTLE FRACTURE WITH PRIOR DUCTILE CRACK EXTENSION

H. Y. Jing , L. X. Huo , Y. F. Zhang and F. Minami( 1) College of Material Science , Tianjin University , Tianjin 300072 , China 2) Osaka University , Japan)

A computation framework for brittle fracture which incorporates weakest link statistics and a microme- chanics model reflecting reflecting local damage of the material is described.The Weibull stress W emerges as a probabilistic fracture parameter to define the condition leading material failure. Unstable crack propa- gation occurs at a critical value of W which may be attained paior to or following some amount of duc- tile crack extension. A realistic model of ductile crack growth using the computation cell methodology is used to define the evolution of near tip stress fields during crack extension. An application of proposed framework to predict the measured geometry and ductile tearing effects on the statistical distributio of fracture toughness for the pipe line steel welded joint is described.

关键词: fracture toughness , null , null

NUMERICAL SIMULATION OF TEMPERATURE FIELD FOR COAT OF COAT-CAST TECHNOLOGY

Z. X. Lee , F. P. Huang and W. Y. Zhang Tianjin University , Tianjin 300072 , China

Using Fourier's conduction equation, a mathematical model of the temperature field for the coat of coat-cast technology is established. The relationship between the thickness, quality of the coat and casting temperature of liquid iron is analyzed. The results show that the coat quality is reliable; the combination of the coat with the base is solid; because foe temperature gradient of the coat is not large, the surface, middle and bond area of the coat are melted completely and the thickness of the coat can reach 2.3mm by using self-melting spraying alloy powder when the casting temperature is higher than 1380℃. In addition, the agreement between the calculated and measured values is good. This paper is of significant meaning for coat-cast technology and the coat quality.

关键词: coat-cast , null , null , null

NUMERICAL MODELING OF DUCTILE CRACK EXTENSION USING COMPUTATIONAL CELL ELEMENTS FOR WELDED JOINTS

H Y Jing , L.X. Huo and Y. F. Zhang(Tianjin University , Tianjin 300072 , China)F. Mnami(Osaka Univeristy , Osaka , Japan)

A 3-D computationalframework was suggested to model stable growth of a macroscopic crack under model I condition. The Gurson-Tverpaaof dilatant plasticity model for voided materials describes the damage process. Fixed-sized, computational cell elements (containing voids) defined over a thin layer at the cmck plane simulate the ductile crack extension. Outside of this layer, the material remains undamaged by the void growth. The micro-mechanics parumeters controlling cmck growth are the thickness Of computational cell layen D, and the initial void porosity, fo. These parameters are calculated through analyses of ductile tearing to match R-curve obtained from testing of deep notch bend specimens for welded joints. The R-curve for the double edge notched tension specimens is eNctively predicted using these pammeters.The predicted R-curve gives a good agreement with the expemment results.

关键词: ductile crack growth , null , null

STUDY ON THE PREDICTIVE METHOD OF BUCKLING DEFORMATIONS OF THIN-PLATE WELDED STRUCTURES

X. Q. Yang , L. X. Huo , Y. F. Zhang and J. X. Yan (School of Material Science and Engineering , Tianjin University , Tianjin 300072 , China)

The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion was proposed in here. It was used the equivalent applied thermal - load to simulate the welding residual stress,therefore the calculation of complex welding distoriton can be transformed into 3D elas- tic structural applied- load analyses, which can reduce the quantities of calculating works effectively. The validation of the method was verified by comparison of the numerical simulation and experimental results. The simulation of buckling distorition for side - walled structrues of paseenger train was per- formed and the calculation was in agreement with measuring results in general. It was shown that the main factors for producing the buckling were the intermittent fillet and ping the during welding the stiffened beams and columns to the panel.The existence of the free edge of panels would reduce the crit- ical buckling stress and enlarge the deflection obviously,but the continuous weld in closed frames didn' t degrade the buckling situation.

关键词: welding buckling distortion , null , null

Geochemical Characteristics of Rare Earth Elements in Intertidal Sediments of Tianjin Coastal Zone

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Geochemical Characteristics of Rare Earth Elements in Intertidal Sediments of Tianjin Coastal Zone

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Geochemical Characteristics of Rare Earth Elements in Intertidal Sediments of Tianjin Coastal Zone

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Geochemical Characteristics of Rare Earth Elements in Intertidal Sediments of Tianjin Coastal Zone