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Journal of Materials Sciences & Technology
Current Issue
2011, Vol.27 No.10
Online: 2011-10-31
Thin Film and Coatings
High Temperature Structural Materials
Iron and Steel
Regular Papers
 
Thin Film and Coatings
865 A.A. Bahgat, H.A. Mady, A.S. Abdel Moghny, A.S. Abd-Rabo, Samia E. Negm
Transport Properties of KxV2O5?nH2O Nanocrystalline Films
Five different compositions of KxV2O5?nH2O (where x=0.00, 0.0017, 0.0049, 0.0064 and 0.0091 mol) were prepared by the sol-gel process. Electrical conductivity and thermoelectric power were measured parallel to the substrate surface in the temperature range of 300-480 K. The electrical conductivity showed that all samples were semiconductors and that conductivity increased with increasing K content. The conductivity of the present system was primarily determined by hopping carrier mobility. The carrier density was evaluated as well. The conduction was confirmed to obey non-adiabatic small polaron hopping. The thermoelectric power or Seebeck effect, increased with increasing K ions content. The results obtained indicated that an n-type
semiconducting behavior within the temperature range was investigated.
2011 Vol. 27 (10): 865-872 [Abstract] ( 114 ) [HTML 1KB] [PDF 493KB] ( 92 )
873 Suh Cem Pang, Wai Hwa Khoh, Suk Fun Chin
Synthesis and Characterization of Magnetite/Carbon Nanocomposite Thin Films for Electrochemical Applications
Stable colloidal suspension of magnetite/starch nanocomposite was prepared by a facile and aqueous-based chemical precipitation method. Magnetite/carbon nanocomposite thin films were subsequently formed upon carbonization of the starch component by heat treatment under controlled conditions. The initial content of native sago starch as the carbon source was found to affect the microstructure and electrochemical properties
of the resulted magnetite/carbon nanocomposite thin films. A specific capacitance of 124 F/g was achieved for the magnetite/carbon nanocomposite thin films as compared to that of 82 F/g for pure magnetite thin films in Na2SO4 aqueous electrolyte.
2011 Vol. 27 (10): 873-878 [Abstract] ( 102 ) [HTML 1KB] [PDF 780KB] ( 116 )
879 Shijie Zhang, Xibin Cao, Yingqiang Luan, Xinxin Ma, Xiaohui Lin, Xianren Kong
Preparation and Properties of Smart Thermal Control and Radiation Protection Materials for Multi-functional Structure of Small Spacecraft
Considering the unique properties of small spacecraft, such as light weight, low power-consumption and high heat flux density, a new kind of lightweight boron carbide (B4C) radiation-protection coating material was proposed. New techniques for preparing LSMO thermal control coating and B4C radiation-protection coating were developed. The sample piece of multi-functional structure was manufactured by using the proposed materials, and a series of performance tests, such as thermal control and radiation-protection behaviors were evaluated. Test results show that: the emissivity of the multi-functional structure varies from 0.42 to 0.86 at 240 K to 353 K and the phase transition temperature is about 260 K. The electron radiation-protection ability of the multi-functional structure is 3.3 times better than that of Al material. The performance index of this multi-functional structure can meet the requirements for space application in on-board electronic equipment.
2011 Vol. 27 (10): 879-884 [Abstract] ( 101 ) [HTML 1KB] [PDF 674KB] ( 102 )
 
High Temperature Structural Materials
885 H.B. Motejadded, M. Soltanieh, S. Rastegari
Dissolution Mechanism of a Zr Rich Structure in a Ni3Al Base Alloy
In the present research, the dissolution mechanism of a Zr rich structure during annealing of a Ni3Al base alloy containing Cr, Mo, Zr and B, was investigated. The annealing treatments were performed up to 50 h at 900, 1000 and 1100 °C. The alloy used in this investigation was produced by vacuum-arc remelting technique. The results show that at the beginning of the process, a mixed interface reaction and local equilibrium (long range diffusion) mechanism controls the dissolution process. After a short time, this mechanism changes and the dissolution mechanism of the Zr rich structure changes to only long range diffusion of Zr element. According to this mechanism, the activation energy of this process is estimated to be about 143.3 kJ?mol-1. Also the
phases that contribute to this structure and the transformations that occur at the final steps of solidification of this alloy were introduced. According to the results, at the final step of solidification, a peritectic type reaction occurs in the form of L+ γ´→ γ+Ni7Zr2 and  γ-Ni7Zr2 segregates from the melt. Following this transformation, γ-Ni7Zr2 eutectic separates from the remaining Zr rich liquid. The solidification process will be terminated by a ternary eutectic reaction in the form of L+→ γ+Ni5Zr+Ni7Zr2.
2011 Vol. 27 (10): 885-892 [Abstract] ( 87 ) [HTML 1KB] [PDF 1383KB] ( 62 )
893 Gang Wang, Lei Xu, Yong Wang, Zhuo Zheng, Yuyou Cui, Rui Yang
Processing Maps for Hot Working Behavior of a PM TiAl Alloy
The hot deformation behavior of a Ti-47Al-2Cr-2Nb-0.2W-0.15B (at.%) titanium aluminide alloy fabricated by pre-alloyed powder metallurgy has been investigated by using the hot compression tests in the temperature range from 950°C to 1300°C and at the strain rates between 10-3 s-1 and 10 s-1. The processing maps have been established to evaluate the optimum hot processing conditions and reveal the instability regions. It is found that the flow stress of the investigated alloy is a strong function of the temperature and the strain rate. The investigated alloy has the optimum hot-working condition at 950°C and 10-3 s-1, since the material undergoes dynamic recrystallization to produce a fine-grained microstructure. At 1250°C and 10-3 s-1, the
alloy exhibits superplastic deformation. At 1300°C and 10-1 s-1, the cyclic dynamic recrystallization with high temperature grain coarsening takes place. The material undergoes flow instabilities at lower temperatures and higher strain rates, as predicted by the instability criterion. The processing maps demonstrate that the strain significantly affected the instability regions. The manifestations of the instabilities have been observed in the form of microvoids, wedge cracks, and surface fractures.
2011 Vol. 27 (10): 893-898 [Abstract] ( 108 ) [HTML 1KB] [PDF 1441KB] ( 74 )
899 X.P. Tan, J.L. Liu, X.P. Song, T. Jin, X.F. Sun, Z.Q. Hu
Measurements of γ/γ´ Lattice Misfit and γ´ Volume Fraction for a Ru-containing Nickel-based Single Crystal Superalloy
A conventional X-ray diffractometer has been used to determine the γ/γ´ lattice misfit and γ´  volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by ω-2θ scan were used to determine the γ/γ´ lattice misfit and γ´ volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection
phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ´ lattice misfit and γ´ volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ´ lattice misfit and γ´ volume fraction of the experimental alloy are approximately -0.2% and 70%, respectively. Furthermore, the γ´ volume fraction calculated by atom microprobe (AP) data is also basically consistent with the experimental results.
2011 Vol. 27 (10): 899-905 [Abstract] ( 113 ) [HTML 1KB] [PDF 830KB] ( 76 )
 
Iron and Steel
906 N. Afsar Kazerooni, M.E. Bahrololoom, M.H. Shariat, F. Mahzoon, T. Jozaghi
Effect of Ringer´s Solution on Wear and Friction of Stainless Steel 316L after Plasma Electrolytic Nitrocarburising at Low Voltages
A plasma electrolytic nitrocarburising (PEN/C) process was performed on stainless steel 316L to improve the surface properties for using as medical implants. A bath was optimised to reduce the required voltage to 150 volts. Aqueous urea-based solutions with 10% NH4Cl were prepared with slightly different amounts of Na2CO3 to optimise the electrolyte composition. The surface and the cross-section morphologies were studied by scanning electron microscopy. The microstructure and the chemical composition of samples were investigated by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) techniques. The microstructure of the outer layer of the coatings was found to be a complex oxide containing Cr and Fe. The wear properties
of the samples were examined by using a pin on disk wear test with Ringer0s solution and were compared with their wear properties in the ambient atmosphere. The Ringer0s solution acted as a lubricant, reducing friction coe±cient. Hardness and roughness were also studied. The bath with the composition of 10% NH4Cl and 3% Na2CO3 exhibited the best tribological properties. The results showed that the tribological properties of treated samples were improved and the wear mechanism was abrasion of the pin.
2011 Vol. 27 (10): 906-912 [Abstract] ( 92 ) [HTML 1KB] [PDF 1309KB] ( 71 )
913 Zhouyu Zeng, Liqing Chen, Fuxian Zhu, Xianghua Liu
Dynamic Recrystallization Behavior of a Heat-resistant Martensitic Stainless Steel 403Nb during Hot Deformation
Dynamic recrystallization (DRX) behaviors of a heat-resistant martensitic stainless steel 403Nb during hot deformation have been investigated by single-pass thermo-mechanical simulative experiment at temperatures of 900-1150°C and strain rates of 0.01-1 s-1. The results show that the true stress-true strain curves of this alloy can be classified into two types, one is of dynamic recovery and the other is of dynamic recrystallization. The DRX in 403Nb alloy is easy to occur at strain rates lower than 0.5 s-1 and deformation temperatures higher than 1000°C. Using regression analysis, the stress multiplier (α) and apparent stress exponent (n) were calculated to be 0.0153 and 3.22, respectively, while the activation energy (Qd) for DRX of 403Nb was calculated to be 367.293 kJ/mol. The constitutive equation of peak stress for DRX was also obtained. Based on P-J method, the critical strain for DRX was accurately  determined. The mathematical models of peak strain and kinetic equation for DRX of 403Nb steel were finally established.
2011 Vol. 27 (10): 913-919 [Abstract] ( 93 ) [HTML 1KB] [PDF 830KB] ( 89 )
920 Pasi P. Suikkanen, Cyril Cayron, Anthony J. DeArdo, L. Pentti Karjalainen
Crystallographic Analysis of Martensite in 0.2C-2.0Mn-1.5Si-0.6Cr Steel using EBSD
The crystallography of martensite formed in 0.2C-2.0Mn-1.5Si-0.6Cr steel was studied using the electron backscattered diffraction (EBSD) technique. The results showed that the observed orientation relationship (OR) was closer to that of Nishiyama-Wassermann (N-W) than Kurdjumov-Sachs. The martensite consisted of parallel laths forming morphological packets. Typically, there were three different lath orientations in a morphological packet consisting of three specific N-W OR variants sharing the same {111} austenite plane. A packet of martensite laths with a common {111} austenite plane was termed a crystallographic packet. Generally, the crystallographic packet size corresponded to the morphological packet size, but occasionally the morphological packet was found to consist of two or more crystallographic packets. Therefore, the crystallographic packet size appeared to be finer than the morphological packet size. The relative orientation between the variants in crystallographic packets was found to be near 60°/<110>, which explains the strong peak
observed near 60° in the grain boundary misorientation distribution. Martensite also contained a high fraction of boundaries with a misorientation in the range 2.5-8°. Typically these boundaries were found to be located inside the martensite laths forming sub-laths.
2011 Vol. 27 (10): 920-930 [Abstract] ( 94 ) [HTML 1KB] [PDF 1188KB] ( 88 )
931 O.H. Ibrahim
Comparison of Impact Properties for Carbon and Low Alloy Steels
The impact properties of hot rolled carbon steel (used for the manufacture of reinforcement steel bars) and the quenched & tempered (Q&T) low alloy steel (used in the pressure vessel industry) were determined. The microstructure of the hot rolled carbon steel contained ferrite/pearlite phases, while that of the quenched and tempered low alloy steel contained bainite structure. Impact properties were determined for both steels by instrumented impact testing at temperatures between -150 and 200°C. The impact properties comprised total impact energy, ductile to brittle transition temperature, crack initiation and propagation energy, brittleness transition temperature and cleavage fracture stress. The Q&T low alloy steel displayed much higher resistance to ductile fracture at high test temperatures, while its resistance to brittle fracture at low test temperatures was a little higher than that of the hot rolled carbon steel. The results were discussed in relation to the di®erence in the chemical composition and microstructure for the two steels.
2011 Vol. 27 (10): 931-936 [Abstract] ( 97 ) [HTML 1KB] [PDF 857KB] ( 130 )
 
Regular Papers
937 Ibrahim Celikyurek, Nese O. Korpe, Tugba Olcer, Remzi Gurler
Microstructure, Properties and Wear Behaviors of (Ni3Al)p Reinforced Cu Matrix Composites
Pure copper and its composites reinforced with Ni3Al particles were produced by powder metallurgy (PM). Ni3Al powders were produced by mechanical ball milling from vacuum arc melted compounds. The Ni3Al powders were characterized by X-ray diffraction (XRD). The microscopy examinations revealed that the Ni3Al particles were distributed uniformly in the matrix. The effects of the particle fraction on the density, electrical conductivity, strength and dry sliding wear resistance of composite were investigated. It was found that the density and electrical conductivity of the composites decrease while the compression yield strength and wear resistance of composites increase with an increase in the particle fraction. The dry sliding wear tests were performed with pin-on-disk geometry. After sliding wear tests, the worn surfaces were examined by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Results have shown that the wear mechanism is oxidative and adhesive.
2011 Vol. 27 (10): 937-943 [Abstract] ( 98 ) [HTML 1KB] [PDF 1147KB] ( 80 )
944 Hakan Colak, Orhan Turkoglu
Effect of Doping and High-Temperature Annealing on the Structural and Electrical Properties of Zn1-XNiXO(0≤X≤0.15) Powders
This paper reported the synthesis, crystal structure and electrical conductivity properties of Ni-doped ZnO powders (i.e. Zn1-XNiXObinary system, X=0, 0.0025, 0.005, 0.0075 and in the range 0.01≤X≤0.15). I-phase samples, which were indexed as single phase with a hexagonal (wurtzite) structure in the Zn1-XNiXObinary system, were determined by X-ray diffraction (XRD). The widest range of the I-phase was determined as 0≤X≤0.03 at 1200°C; above this range the mixed phase was observed. The impurity phase was determined as NiO when compared with standard XRD data, using the PDF program. We focused on single I-phase ZnO samples which were synthesized at 1200°C because of the widest range of solubility limit at this temperature. It was observed that the lattice parameters a and c of the I-phase decreased with Ni doping concentration. The morphology of the I-phase samples was analyzed with a scanning electron microscope. The electrical conductivity of the pure ZnO and single I-phase samples were studied by using the four-probe dc method at temperatures between 100 and 950°C in air atmosphere. The electrical conductivity values of pure ZnO and 3 mol% Ni-doped ZnO samples at 100°C were 2×10-6 and 4.8×10-6Ω-1?cm-1, and at 950°C they were 1.8 and 3.6Ω-1?cm-1, respectively. In other words, electrical conductivity increased with Ni doping concentration.
2011 Vol. 27 (10): 944-950 [Abstract] ( 106 ) [HTML 1KB] [PDF 862KB] ( 68 )
951 Amir Etaati, Kamran Dehghani
Microstructural evolution of NiTi47.7Cu6.3 alloy during hot deformation
In the present work, the hot workability and microstructural evolution of NiTi47.7Cu6.3 (at.%) shape memory alloy were investigated by using wedge-rolling test. The wedge specimens were subjected to hot rolling at the temperatures of 700-1000°C. The microstructural evolutions at the strains of 0.05, 0.15, 0.2, 0.25 and 0.3 were then characterized by optical microscopy and scanning electron microscopy (SEM) as well as energy dispersive spectrometry (EDS) technique. Depending on the deformation temperature and strain, the dynamic recrystallization (DRX) could occur, leading to the refining of the  microstructure. At low temperatures of 700 and 800°C, there was no sign of DRX at all studied strains. At these temperatures, the formed fine
needle-like precipitates pinned the grain boundaries and prevented them from bulging/migration. By contrast, at higher temperatures of 900 and 1000°C, the DRX took place at the critical strains lower than 0.25 and 0.15, respectively. However, at higher temperatures, strain-induced-boundary-migration (SIBM) mechanism resulted in the formation of DRX grains.
2011 Vol. 27 (10): 951-960 [Abstract] ( 117 ) [HTML 1KB] [PDF 1678KB] ( 83 )

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