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
Z. Li
,
Y.L. Yand
,
J.K Xi
,
J.X. Qu and H. S. Shao (Department of Materials Engineering
,
Luoyang institute of Technology
,
Luoyang 471039
,
China)(Beijing Graduate School
,
China University of Mining and Technology
,
Beijing 100083
,
China)
金属学报(英文版)
Annealing treatment has a strong effect on mechanical Properties of cold worked tungsten-nickel-iron heavy alloys. A 93W-4.5Ni-2.5Fe alloy swaged 15% was annealed from 500 to 1350℃ to investigate the changes in microstructure and their effects on mechanical properties. Recrystallization of W particles takes place during annealing treatments above 800℃ and the microhardnesses reduces rapidly. High density of dislocations in the, matrix phase after annealing treatment at 1350℃ suggests that recrystallization of the matrix phase has not taken place. A small decrease in microhardness of the matrix phase is caused by recovery during the annealing treatments.The changes in mechanical properties of swaged and annealed 93W-4.5 Ni-2.SFe alloy are mainly due to the changes in microstructure of W particles because of their recrystallization.
关键词:
: 93 W-4.5 Ni-2. 5 Fe alloy
,
null
,
null
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
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:
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
Author M.F. Geng1)
,
T. Wang1) and X.A. Zhang2) 1) Department of Special Metal Materials and Products
,
Luoyang Ship Material Research Institute
,
Luoyang 471039
,
China2) Mechanical Properties Laboratory
,
Beijing Institute of Aeronautical Materials
,
Beijing 100095
,
China Manuscript received18 October 1998
金属学报(英文版)
The effects of cyclic loading on crack growth, fracture feature and rupture life of superalloy GH2132 have been studied in the present paper. The crack growth tests were carried out at 550 on compact tension specimens under a wide range of load levels and various periods of hold time, and the fracture surfaces were examined on a scanning electron microscope. The results show that, for both static and cyclic creep, Stage-I of crack growth is related with initial test stress, during which the crack extension is about 0.5mm, and that the final effect of cyclic loading on rupture life depends on the counteraction of its two reversed effects on crack growth rate before and after the point n=0.2.
关键词:
cyclic creep
,
null
,
null
,
null
,
null
,
null
K.K. Zhang
,
D.R. Chen
,
J. Xue
,
D. W. Sun and H.C. Li( 1) Department of Materials Engineer
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China 2) Luoyang Institute of Technology
,
Luoyang 471039
,
China 3) CITIC Heavy)
金属学报(英文版)
Base on a vast amount of testing and calculations for the welding thermal cycling curves of different testing points in fusion welding (TIG welding, gas welding) HAZ of zinc-based alloy with low melting points, this paper defines the welding thermal cycle parameters of microstructure stimulation of HAZ by zinc-based alloy fusion welding process. On the principle of which the microstrnct,are and harkness of the testing points in simulation specimens are basically correspondence with that of actual welding HAZ, the microstructure simulation of testing points Tm=370O℃. 305℃) of ZA12 alloy by fusion welding is carried out by the means of omhic-heating welding thermal simulation tester. The study results of the abrasion-resistance of simulation specimens HAZ by fusion welding process indicates that the abmsion-resistance is closely related to the form of eutectoid microstructure in or in the structure.
关键词:
zinc-based alloy
,
null
,
null
,
null
,
null
M.F. Geng(Luoyang Ship Material Research Institute
,
Luoyang 471039
,
China)
金属学报(英文版)
The crack growth behavior and fracture feature of superalloy GH2132 (equivalent to A286) under creep-fatigue conditions have been studied in the present paper. The tests were carried out at 550℃ under various cyclic freqencies (hold time) and load levels,and the fracture surfaces were examined by using a scanning electron microscope. It is shown that the fracture mode of creep-fatigue and the effect of cyclic loading on crack growth change with the growth of crack and the increase of net-section stress,and both are reversed when the net-section stress is up to the yield stress of material.When σn <σ0.2, cracking is predominantly cycle-dependent transgranular and cyclic loading accelerates creep crack growth, whereas when σm>σ0.2, the case is reversed.
关键词:
creep-fatigue
,
null
,
null
,
null
,
null
,
null
