ZHANG Rong
,
ZHOU Lubin
,
Northwestern Polytechnical University
,
Xi'an
,
ChinaZHENG Wenlong
,
HUA Huizhong
,
Shanghai Research Institute of Materials
,
Shanghai
,
China ZHANG Rong
,
Lecturer
,
Department of Applied Physics
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China
金属学报(英文版)
The behaviour towards corrosion fatigue of low carbon bainite steel with various microstructures after tempered at different temperatures has been examined. The susceptibility of the steel to corrosion fatigue may be improved by tempering at 300℃.
关键词:
corrosion fatigue
,
null
,
null
,
null
K. Zhang
,
YQ. Wang
,
B.L. Zhou
,
YH. Zhou and H.L. Li (Institute of Metal Research
,
Chinese Academy of Scie11ces
,
Shenyang 110015
,
China International Center of Materials Physics
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China Dept. of Materials Science and Engineering
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
The mechanical properties and deformation mechanisms of unidirectional carbon fiber reiopreed magnesium composites under tensile loading are studied. Two different materials are used as fiber coatings: a single silica and a gradient C/SiC/SiO2. The results show that, under the same preparation conditions, composite with the former coating is broken in a non-cumulative mode and its failure stress is rather low. Conversely, the latter coating demonstrates much better efficiency and the cormsponding composite is broken in a cumttlative mode.
关键词:
tensile properties
,
null
,
null
Q. Y Pan
,
WD. Huang
,
YM. Li
,
X. Lin
,
YH. Zhou and X.C. Yan( State Key Lab. of Solidification Processing
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China ( Laser Processing Center
,
Tianjin College of Textile Technology
,
Tianjin 300160
,
China )
金属学报(英文版)
A novel wide-band laser cladding system, with high rate of cladding, has been developed in the present work. The system mainly consisted of a 5kW CO2 laser, an automatic Fowder feeder and a wide-band scanning rotative polygon mirmr which can produce a linear or rectangular focused laser beam. Using this system, a Ni-Cr-Si-B alloy powder was cladded on the sudece of tgpe 321 austenitic stainless steel in onder to improve its wear and cormsion resistance. The pitting cormsion, high temperuture oxidation and wear tests were conducted in onder to evaluate the propertles of the laser cladded layer. The results demonstrated that the cladded layer can significantly improtte the adhesive wear and pitting cormsion resistance of the substmte. Moreover,the cladded layer exhibited good oxidafion resistance, which is almost the same as that of GMR-235D N-based superalloy.
关键词:
austenitic stainless steel
,
null
,
null
,
null
N. Wang and B. Wei (Laboratory of Materials Science in Space
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)(Laboratory of Materials Science in Space
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
The Ag-50wt%Cu hypereutectic alloy was solidified in a 3m drop tube. It is .revealed that with the decrease of droplet size, the strnctural morphology transformed from the dendrites with long trunk and thin short secondary arms to fine dendritic structures.The calculations based on LKT dendritic growth model indicate that dendritic growth is dominantly controlled by solute diffusion within the whole undcreooling regime.However, the influence of thermal diffusion-controlled growth becomes stronger above a critical undercooling about 268K. The refinement of dendritic structure is caused by large amounts of nuclei within droplet. Moreover, it is estimated that when droplet diameter is smaller than 300μm, the undercooling and growth velocity are fanger than 268K and 290mm/s respectively, while the solute impping effect may occur. Compared with Ag-15wt%Cu hypoeutectic alloy, there is no evident feature of dendritic-toequiaxed transition for Ag-50wt%Cu hypereutectic alloy, which is consistent with the calculation results of dendritic breakap time.Keuwords: Ag-Cu alloy; rapid solidification; undercooling; dendritic growth
关键词:
Ag-Cu alloy
,
null
,
null
,
null
R.Shi
,
G.X.Hu
,
H.J.Li and M.K.Kang (The State Education Commission Open Research Laboratory for High Temperature Materials and Testing
,
Shanghai Jiao Tong University
,
Shanghai 200030
,
China)(Department of Materials Science and Engineering
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
The steady-state creep behavior of unidirectional C/C(1-D-C/C) composite with pyrolytic carbon matrix was investigated at high temperatures up to 2160℃ and under tensile stress from 133.83 to 213.46MPa. Based on the creep experiment of single specimen method, the apparent activation energy and the stress exponent for steadystate creep were determined by the use of a self-made apparatus and an auto-testing system. Value of apparent activation volume is provided and the creep mechanism has also been discussed.
关键词:
1-D-C/C
,
null
,
null
YC. Liu
,
G.C. Yang
,
YL. Lu and Z.G. Zhu (State Key Lab. of Solidification Processing
,
Northwestern Polytechnic University
,
Xi'an 710072
,
China Laboratory of Internal Friction and Defects in Solids
,
Chinese Academy of Science
,
Hefei 230031
,
China )
金属学报(英文版)
The effects of cerium modification and extrusion on the resultant damping behavior and mechanical properties of the as-sprayed high silicon alloy ZA27 were investigated in an thort to develop a new functional material possessing high damping capacity and good mechanical properties. The damping capacity, as well as the rslative dynamic modulus, was tneasured at frequencies of 1 and 4 Hertz over the 30 to 200℃runge. At below 80℃ the as-sprayed materials appear to be approximately Asquency independent. Above 80℃, the,naterials becotne temperature sensitive, exhibiting the highest damping for the lowest hequency. The extruded, as-sprayed high silicon alloy ZA27 modified by cerium has the highest damping capacity and elongation values among them. The micro8tructure of the as-sprayed high silicon alloy ZA27 modified by 0. 5 wt% cerium was made up of fine lamellar eutectoid, porositg, a light dot-like phase and a polygonal silicon-rich phase. Finally, the opemtive damping tnechanisms were discussed in light of the data obtained hem characterization of microstructure and damping capacity. The high damping capacity was attributed primarily to phase interface thermoelastic damping between the lamellar phases with various substrvctures,except for the grain refinement.
关键词:
spray deposition
,
null
,
null
,
null
J. Feng
,
W.D. Huang
,
X. Lin
,
T. Li
,
Y.F. Xue and Y.H. Zhou(State Key Lab. of Solidilication Processing
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
In order to investigate the response of cellular spacing to the variation of growth velocity under near-rapid directional solidification condition, Al-0.53wt%Zn alloy is directionally solidified with Bridgman apparatus. The results show that at the given temperature gradient the obtained microstrvctures are all cells and there exists a wide distribution range of cellular spacing. The maximum, λmax, minimum, λmin, and average cellular spacing, λ, as functions of growth rate, V, can be given by λmax=948.51V-0.4961, λmin= 661.16V-0.5015 and λ=412.41V-0.5049, respectively. The experimental results are compared with that predicted by KGT model, and a good agreement is found. Moreover,it is found that the average cellular spacing is also remarkably history-dependent.
关键词:
Al-Zn alloy
,
null
,
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）
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:
Xincai LIU
,
Jin PAN
,
Zhifeng XU
,
Jianping ZHUANG
,
Min LIU and Dongming YU (Nanchang Institute of Aeronautical Technology
,
Nanchang 330034
,
China)Zhengxing SH and Hengzhi FU(Northwestern Polytechnic University
,
Xi'an 710072
,
China)
材料科学技术（英）
To obtain excellent magnetic properties of machinable REPM prepared by directional solidification (DS) technology Space A, a composition area with θ=0°~5° where easy axis is parallel to solidified direction of alloys, has been established in Zr-Sm-La-Co-Cu-Fe system. In 2/17+1/5+Co, and 2/17+1/5 region near Co phase of Space A, one obtains:Vf = 80.933 - 2.739Zr - 1.828Sm - 0.773Co - 0.147Cu + 0.415Fe + 0.218LaNonequilibrium solidification process of alloys in 2/17+1/5+Co region, is as follows: L→Co,L→2/17, L+2/17→1/5 and L→1/(5-x)+1/(5+x). The product of partially completed peritectic reaction, and 1/(5-x) and 1/(5+x) phases can all be transformed into a homogeneous 1/5 phase after solution treatment in 1413 K for 5 h. Containing 3~6% Co phase magnetically hardened by 0.5~2.5% V, the DS magnets have been achieved with both improved toughness and excellent coercive force of 520 kA/m.
关键词:
