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INTERACTION OF PRECIPITATION AND RECRYSTALLIZATION IN RAPIDLY SOLIDIFIED Cu-Cr-Zr-Mg ALLOY

Liu , B.X. Kang , X.G. Cao , J.L. Huang , B. Yinand H.C. Gu (Institute of Materials Science and Engineering , Xi'an Jiaotong University , Xi'an 710049 , China)(Institute of Materials Science and Engineering , Xi'an Jiaotong University , Xi'an 710049 , China)( Department of Materials Engineering , Luoyang Institute of Technology , Luoyang 471049 , China)( Department of Materials Engineering , Luoyang Institute of Technology , Luoyang 471049 , China)( Department of Materials Engineering , Luoyang Institute of Technology , Luoyang 471049 , China)( Department of Materials Engineering , Luoyang Institute of Technology , Luoyang 471049 , China)

金属学报(英文版)

In this paper; the recrystallization process during aging for a rapidly solidified Cu-Cr-Zr-Mg alloy has been investigated. It is found that the discotinuous crystallization process has been partially retarded by the ultra-fine and dispersed precipitation upon aging after deformation. Thus, a phenomenon of combined in situ and discontinuous recrystallization has been observed in the rapidly solidified Cu-Cr-Zr-Mg alloy.On the nucleation and growth of recrystallization, the precipitated phases are coarscned and dissolved in the front of grain boundaries following a re-precipitation in the recrystallization area,which results in the much more dispersed precipitates.

关键词: rapid solidification; Cu-Cr-Zr-Mg alloy; aging precipitation; recrystallization

ATOMIC SCALE MECHANISM OF RESTRAINED EMBRITTLEMENT IN AMORPHOUS Fe_(78)B_(13)Si_9 ALLOY BY ELECTRIC PULSE RAPID ANNEALING

J.L. Huang , X.G. Cao , E. Sukedai , S. Yamasaki , and H.C.Gu(Department of Materials Engineering , Luoyang Institute of Technology , Luoyang 471039 , China)(Department of Mechanical Engineering , Okayama University of Science , 1-1 Ridai-Cho , Okayama City , Okayma 700 , Japan)(Institute of Materials Science and Engineering , Xi'an Jiaotong University , Xi'an 710049 , China)

金属学报(英文版)

The direct observations of the atomic arrangements in both conventional furnace annealed and electric pulse rapid annealed Fe78B13Si9 amorphous alloy have been conducted by the lattice imaging technique in a higt resolution electron microscope. The results showed that the embrittlement of the alloy was related to the extent of atomic rearrangements during the annealing processes. The embrittlement of the alloy after 1hour conventional furnace annealing at about 270℃ is caused by the sufficient atomic rearrangements which are characterized by the growth of some bct Fe3B-like atomic short range ordering regions already existed in the as-quenched structure. Electric pulse rapid annealing can effectively retard the above-mentioned atomic rearrangements and thus restrain the embrittlement. The embrittlement only occurs when certain amount of bcc α-Fe nanocrystals are precipitated in the amorphous matrix during electric pulse rapid annealing.

关键词: Fe_(78)B_(13)Si_9 amorphous alloy , null , null , null

A MODEL FOR NUMERICAL CALCULATION OF UNSTEADY TEMPERATURE FIELD

S. X. Wang , D. S. Zheng and Y. L. Liu 1) Department of Material Engineering , Luoyang Institute of Technology , Luoyang 471039 , China 2) Luoyang Copper (Group) Co. , Ltd , Luoyang , China

金属学报(英文版)

The model established in this paper for calculating the unsteady temperature field, in which physical parameters varies with temperatures, is simplified as compared with the classical one by defining the heat conductivity as function of temperature and dealing with the latent heat of phase transformation and boundary conditions. The results show that the probability of absolute error less 2℃ between the calculated and measured values in temperature field calculation reaches above 80%.

关键词: temperature field , null , null

Damping Capacity and Creep Resistance of Spray Deposited High Silicon Alloy ZA27

Yongchang LIU , Gencang YANG and Yili LU (State Key Lab. of Solidification Processing , Northwestern Polytechnic University , Xi'an 710072 , China)Liushuan YANG(Dept. of Materials Science and Technology , Luoyang Institute of Technology , Luoyang 471039 , China

材料科学技术（英文）

High Al zinc-based alloys are widely used in industry for their good ambient temperature mechanical properties and damping capacity. With the rise of service temperature its damping property increases but mechanical property decreases greatly Here two ways-alloying and spray deposition technique were adopted to improve the service temperature limitation of the alloy ZA27 in an effort to develop a new functional material with high damping capacity and good elevated temperature mechanical property. The effects of addition of 5 wt pct of Si Qn the damping behaviour and elevated temperature creep resistance of alloy ZA27 were investigated. The damping capacity, as well as the relative dynamic modulus, was measured at frequency of 1,4 Hz over the 303 to 573 K. No peak phenomenon was observed for the specimens tested in the temperature range of interest. Experimental results indicated that the damping capacity of the deposited material was 2.8 times higher than that of the cast one at 305 K. The ball hardness values were used to evaluate the creep property and the creep activation energy of the deposited material is 3.9~5.7 kJ per mol higher than that of the as-cast one. The creep rate formuIation was also derived. Finally, the operative damping and creep mechanisms were discussed in the light of the data obtained from its characterization of microstructure, damping capacity and creep reslstance

关键词:

MEASUREMENT AND APPLICATION OF PHYSICAL PARAMETERS IN UNSTEADY HEAT CONDUCTION

S. X. Wanng , D. S. Zheng , Y. L. Liu 1) Department of Material Engineering , Luoyang Institute of Technology , Luoyang 471039 , China 2) Luoyang Copper (Group) Co. , Ltd , Luoyang , China

金属学报(英文版)

As far as the accuracy of calculating unsteady temperature field is concerned, it is very important to find the accurate physical parameters such as specific heat, thermal conductivity, latent heat of phase transformation and surface heat flux. The model for calculating H and Q is established in this paper. The measurement methods and data processing for physical parameters such as volume specific heat C, thermal conductivity k, volume latent heat of phase transformation c1 and surface heat flux are introduced The physical parameters of 1Cr18Ni9Ti and 45 steels and the surface heat flux for 1 Cr18Ni9Ti probe cooled in water,10% NaCl water and oil with different temperatures are measured, respectively. These data show that the probability of absolute error less than 2* C between the calculated and measured values in temperature field calculation reaches above 80% if using the above physical parameters, which provides a reliable technology basis for precise calculation of temperature field.

关键词: unsteady temperature field , null

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