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Journal of Materials Sciences & Technology
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1997, Vol.13 No.1
Online: 1997-01-28
Articles
 
Articles
1 D.L. Chen; B. Weiss and R.Stickler(Institute for Physical Chemistry-Materials Science, University of Vienna, Waehringer Strasse 42, A-1090 Vienna, Austria Zhongguang WANG)(State Key Lab. for Fatigue and Fracture of Materials, Institute of Metal Research,
Brief Review and Reconsideration of Fatigue Crack Closure Effect in Materials
The state-of the-art of fatigue crack closure effect, involving the mechanisms, measurements,models, evaluation methods, innuencing factors and existing problems is briefly reviewed. Attention is concentrated on a new consideration of closure effect and a re-definition of the effective d riving force for the propagation of a fatigue crack. A theoretical basis fOr measuring the closure effect is established. The proposed closure concept takes into account the role of the lower portion of loading cycle below the opening load. The conventionaI closure concept is proven to be correct only for some extreme cases which are practically non-existent fOr engineering materials. A miniature strain gauge tech nique is developed to measure the crack closure. Stressratio-change tests at threshold level clearly indicate the shortcomings of the conventional closure concept, and the validity of the newly-proposed closure concept. The application of the proposed concept can give rise to a new method for the determination of the effective fatigue threshold of materials. If the fatigue threshold is measured at a sufficiently negative stress ratio (R
1997 Vol. 13 (1): 1-14 [Abstract] ( 283 ) [HTML 1KB] [PDF 1788KB] ( 375 )
15 Xingjun LIU; Mn JIANG; Shiming HAO and Rongwen YUAN(Dept. of Materials Science and Engineering, Northeastern University, Shenyang 110006, China)
Calculation of Phase Equilibria between Solid Solutions with Magnetic Transition by the Cluster Variation Method
By using the geometric analysis of grand potential, the molar grand potential-effective chemical potential curve of solution with magnetic transition can be obtained from the relevant molar free energy diagram, and it is shown that the grand potential and effective chemical potential can be separated into paramagnetic and magnetic terms. In addition. the CVM has been combined with the present magnetic transition free energy model such as M .Hillert and T.Nishizawa's models to calculate phase equilibria between solutions with magnetic transition, and this combined method has been applied to the α/γ phase equilibrium in the Fe-Mn binary system and found to be feasible.
1997 Vol. 13 (1): 15-20 [Abstract] ( 233 ) [HTML 1KB] [PDF 621KB] ( 259 )
21 Yinan NING and Yuantao NING (Kunming Institute of Precious Metals, Kunming 650221, China)
Alloying Behaviour and Atomic Size Effect in Palladium-rich Pd-RE Systems
The alloying behaviour, including solid solubilities of rare-earths as well as the formation and stability of various intermediate phases in palladium-rich Pd-RE systems were studied by means of the atomic size factor and the reduced transition temperatures. A strong analogy is observed in the plots of the reduced transition temperatures of various intermediate phases against the atomic numbers of rare-earths, and the law proposed by Hume-Rothery and Raynor for dependence of liquidus temperature on atomic radius in simple alloy systems has been extended to more complicated alloy systems.
1997 Vol. 13 (1): 21-26 [Abstract] ( 279 ) [HTML 1KB] [PDF 1304KB] ( 247 )
27 Aiping XIAN; Yiyin SAN; Dun ZHANG and Yikang WANG(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China)Heping SUN(Liaohe Oil Field Machinery Plant, Panjin 124209, China)
Caustic Failure of Thermal Insulated Tubing in Steam Flooding
The coupling of the pre-stressed thermal insulated tubing string broke down inside the steam flooding wells, after the tubing were used in high temperature and high pressure steam for about two years. With further check, it was found that most of the weld joints between the inner and outer tubing also cracked. The failure analysis for the accidents has been carried out by the analysis of chemical composition for the steels, microstructure observation, mechanical property tests, and the investigation of the service environment etc.. The results show that the early damage of the pre-stressed thermal insulated tubing string is mainly induced by the caustic stress corrosion, which can be strengthened by an unstable microstructure of the coupling serviced at high temperature for a long time. Moreover, the high pre-stress design on the thermal insulated pipe for the cyclic steam injection may be not suitable to the situation of steam flooding, which would result in the weld joint cracking.
1997 Vol. 13 (1): 27-36 [Abstract] ( 269 ) [HTML 1KB] [PDF 5735KB] ( 415 )
37 Jianhua LIU; Xiangyi ZHANG and Yangzeng ZHENG (Dept. of Materials Engineering, Yanshan University, Qinhuangdao 066004, China)Jinhua ZHAO and Riping LIU (Institute of Physics, Chinese Academy of Sciences , Beijing 100080, China)(Present address: Institute
Ordering of the α-Fe(Si) Crystallization Phase in Annealed Fe_(73.5)Cu_1Mo_3Si_(13.5)B_9 Alloy
The ordering of the α-Fe(Si) crystallization phase in annealed Fe73.5Cu1Mo3Si13.5B9 alloy has been studied using XRD method. The α-Fe(Si) phase in Fe73.5Cu1Mo3Si13.5B9 alloy annealed at 460℃ for 1 h consists of the DO3-type ordered region with spherical shape and disordered region. The size of DO3 ordered region increases with the annealing temperature. When the annealing temperature is 560℃, the size of the ordered region in the α-Fe(Si) grain is 14.0nm,which is nearly as large as that of the α-Fe(Si) grain (14.2 nm) and the degree of order of the α-Fe(Si) phase is about 0.78. When Fe73.5Cu1 Mo3Si13.5B9 amorphous alloy is annealed at 520℃, with the increment of the annealing time, the shape of the DO3 ordered region in the α-Fe(Si) phase is spheroidal at the beginning of the annealing and becomes spherical and has asize of 12.8 nm when the annealing time is 60 min. In addition, the DO3 superlattice lines of the α-Fe(Si) phase will vanish if Fe73.5Cu1Mo3Si13.5 B9 amorphous alloy is annealed for 1 h at 750℃.
1997 Vol. 13 (1): 37-40 [Abstract] ( 241 ) [HTML 1KB] [PDF 404KB] ( 234 )
41 Yuxiong LU; Douxing LI;Dehai PING; Jing BI and Zongyi MA (Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China)
Microstructure of TiB Whisker Reinforced Ti Matrix Composite
The composite of Ti matrix with TiB whisker reinforcement has been successfully fabricated. The content of TiB whisker in Ti matrix can reach about 30 vol. pct. Metallographic examination,morphology and microstructure of TiB whisker, interface structure between TiB whisker and Ti matrix were investigated using optical microscope, SEM, TEM and HREM technology. The diameter distribution of TiB whisker is from 0. 1 μm to 3.5 μm and the aspect ratio of TiB whisker is from 10 to 20. The cross-section of whisker is generally polygon. Because of good compatibility between TiB whisler and Ti matrix it is identified that there is no obvious interaction of Ti matrix with Ti B reinforcement and TiB whisker reinforced Ti matrix composites have excellent elevated properties.
1997 Vol. 13 (1): 41-44 [Abstract] ( 237 ) [HTML 1KB] [PDF 2172KB] ( 305 )
45 Y.H.ZHU and J.Juarez Islas (Instituto de Investigaciones en Materiales, UNAM, Apdo.P.70-360, Mexico D.F.04510, Mexico)
Tensile Stress Induced Phase Transformations in Zn-Al Alloy
Both furnace cooled and as-cast eutectoid Zn-Al alloys were investigated under external tensile stress at 100℃. It was observed that the external tensile stress caused decomposition of two metastable phases η'T and η'S which derived from both original state of the alloy, and a phase transformation, αf +ε→T' +η, in both furnace cooled and as-cast eutectoid Zn-Al alloys. Also spheroidized structure formed partially during tensile testing. Superplasticity of the alloy has been discussed correlating with the phase transformations and microstructural changes.
1997 Vol. 13 (1): 45-49 [Abstract] ( 290 ) [HTML 1KB] [PDF 2868KB] ( 300 )
50 Deheng ZHANG(Dept. of Physics, Shandong University, Jinan 250100, China)Honglei MA(Institute of Optoelectronic Materials and Devices, Shandong University, Jinan 250100, China)
Conduction Properties and Scattering Mechanisms in F-doped Textured Transparent Conducting SnO_2 Films Deposited by APCVD
Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16～400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 :F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.
1997 Vol. 13 (1): 50-56 [Abstract] ( 300 ) [HTML 1KB] [PDF 1736KB] ( 314 )
57 Xingzhong ZHAO; Jiajun LIU and Baoliang ZHU (Tsinghua University, Beiing 100084, China)Cuiyuen WANG (Zhengzhou Research Institute of Mechanical Engineering, Zhengzhou 450002, China)
Laboratory Assessment of Lubricants for Wheel/Rail Lubrication
The antiwear properties of two wheel/rail lubricating oils were tested and compared on an Amsler machine. Under same testing conditions, oil A (developed by authors) showed much better wear resistance and higher load-carrying capacity than oil B (imported from abroad). The X-ray diffraction (XRD) analyses of the worn surfaces showed that different extreme pressure (EP) lubricating films were formed on the surfaces when the rollers were lubricated with different oils under boundary Iubrication condition. The EP film of oil A was a composite film containing three compounds, FeO, FeSx and FeP, while oil B formed only a simple EP film of FePO4. The composite EP film showed lower shear strength and better antiwear property than the simple EP film,which brought about different wear resistance of the two wheel/rail lubricating oils.
1997 Vol. 13 (1): 57-60 [Abstract] ( 233 ) [HTML 1KB] [PDF 341KB] ( 308 )
61 Jianmin LI; Mingxiu QUAN and Zhuangqi HU (National Key Lab. of RSA, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015, China)
Annealing Embrittlement in Fe-Mo-Si-B Amorphous Alloy
Annealing at Ta=200℃ or so, the enhancement in the average tensile fracture strength of as-quenched (Fe0.99Mo0.01)78Si9B13 metallic glass increases about 7～8%. The origin of the annealing embrittlement at 244℃ in the metallic glass (Fe0.99 Mo0.01)78Si9B13 was revealed that due to the formation of nanoscale granular with bcc structure resulting in the stress localization.The temperature of annealing embrittlement was in agreement with the calculated value from Tbcc=0.637Tc (Tc is the crystallized temperature), based on micromechanism of crystallization of metallic glass.
1997 Vol. 13 (1): 61-64 [Abstract] ( 232 ) [HTML 1KB] [PDF 2013KB] ( 260 )
65 Liping ZHENG (Shanghai Institute of Nuclear Research, Chinese Academy of Sciences, Shanghai 201800, China)Risheng LI and Shuyou LI(Lab. of Atomic Imaging of Solids, Institute of Metal Research, Chinese Academy of Sciences,Shenyang 110015, China)
Simulation of Isotopic Angular Effects under Ion Bombardment of a~(92)Mo-~(100)Mo Target
Under 5 keV Ar ion bombardment of a 92Mo-100Mo target, we have investigated isotopic angular effects by means of the static and the dynamic Monte Carlo programs. Our calculated results are in quantitative agreement with the measured and other calculated results. The conclusion consistences among theories. simulations and measurements are also discussed.
1997 Vol. 13 (1): 65-68 [Abstract] ( 258 ) [HTML 1KB] [PDF 463KB] ( 250 )
69 S. G.Psakhie; A. YU.Smolin; E. V.Shilko ; S.Yu.Korostelev, A.I.Dmitriev and S. V.Alekseev (Institute of Strength Physics and Materials Science of the Russian Academy of Sciences,Siberian Branch 634055, Tomsk, Russia)
About the Features of Transient to Steady State Deformation of Solids
The features of transient to steady state deformation of solids are theoretically investigated.Modeling of various types of loading was carried out by the Movable Cellular Automata method.A stress state of material at the stage of transient to a steady state is shown to be essentially non-uniform, that may in its turn result in stable structures in velocity field of particles of the material. It may also influence development of deformation at the further stages.
1997 Vol. 13 (1): 69-72 [Abstract] ( 239 ) [HTML 1KB] [PDF 541KB] ( 271 )
73 M.Arif and N.Ikram (Centre for Solid State Physics, Punjab University, Lahore, Pakistan)A.Shaukat(Dept. of Physics, Punjab University, Lahore, Pakistan )
Electrical Resistivity due to Short-range Order in Ni_2Cr
Residual electrical resistivity of Ni2Cr alloy due to short-range order (SRO) has been calculated at a temperature which is above the transition temperature, Tc, from long-range order to shortrange order. The atomic form factors for Ni and Cr are calculated in the pseudopotential formalism. We discuss the result of our calculations indicating a decrease in the value of residual electrical resistivity due to SRO in the light of experimental resistivity studies done on Ni72.5Cr27.5 and Ni65Cr35.
1997 Vol. 13 (1): 73-75 [Abstract] ( 239 ) [HTML 1KB] [PDF 348KB] ( 282 )
76 V. O.Nwoko and O. O. Onyemaobi (Dept. of Materials and Metallurgical Engineering, Federal University of Technology, Owerri, Nigeria)
Beneficiation Study on a Nigerian Baryte Ore for Industrial Use
Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.
1997 Vol. 13 (1): 76-78 [Abstract] ( 269 ) [HTML 1KB] [PDF 314KB] ( 566 )
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1997 Vol. 13 (1): 79-80 [Abstract] ( 230 ) [HTML 1KB] [PDF 1403KB] ( 228 )

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