Materials Literature
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We examine the real space structure and the electronic structure (particularly Ce4f electron localization) of oxygen vacancies in CeO(2) (ceria) as a function of U in density functional theory studies with the rotationally invariant forms of the LDA+U and GGA+U functionals. The four nearest neighbor Ce ions always rel…
Abstract A critical review of the literature on the various aspects of natural fibers and biocomposites with a particular reference to chemical modifications is presented in this paper. A notable disadvantage of natural fibers is their polarity which makes it incompatible with hydrophobic matrix. This incompatibility…
Reaction of magnesia-chrome (MgO-Cr2O3) brick with molten MgO-Al2O3-SiO2-CaO-FetO slag using electric furnace static corrosion test method was investigated by X-ray diffraction (XRD), optical polarized microscopy (OPM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), scanning transmission ele…
The globularization behavior of ELI grade Ti-6Al-4V alloy having different initial lamellar structures during multi-step forging under non-isothermal condition was investigated. The samples with either a thin or thick lamellar structure, which were produced from β annealing followed by different cooling conditions, we…
ZrO2 substituted polycrystalline BaTi2O5, Ba(Ti1−yZry)2O5, (BT2Z), was prepared by arc-melting and the dielectric property was investigated by AC impedance spectroscopy. The length of a-axis increased from 1.6895 to 1.6952 nm and that of c-axis increased from 0.9411 to 0.9436 nm with increasing y up to 0.06. The b-axi…
Materials suitable for spintronic devices are searched in two systems Fe2(Cr1−xMnx)Si and (Fe1−xCox)2MnSi. The desired characteristics are: high spin polarization, stability of ferromagnetism and high Curie temperature. The first is investigated by considering the density of states and the velocity at the Fermi energy…
High purity (99.999%) aluminium was subjected to Equal-Channel Angular Pressing (ECAP) at room temperature for up to 8 passes through route BC using a die having a channel angle of 90°. Hardness measurements and tensile tests were conducted at room temperature with respect to the number of ECAP passes. It is shown tha…
The effects of manganese and/or carbon on the grain refinement of Mg-3Al alloy have been investigated in the present study. Significant grain refinement was obtained for the Mg-3Al alloy modified with either carbon or Al-Mn master alloy. There existed an optimal content of 0.1∼0.2 mass%Mn to obtain refining grain size…
A Cu-6.5 mass%Co alloy containing a fine dispersion of ferromagnetic Co precipitates in the Cu matrix is processed by ECAP and measurements of coercivity are carried out after ECAP with different numbers of passes and different processing routes. Changes in particle size and shape including crystal structures are exam…
Frictional wear resistance is one of the important properties of metallic biomaterials. Surface hardening treatments such as oxidizing, nitriding and ion implantation tend to be applied for improving the wear resistance of titanium and its alloys. The simple gas nitriding process is expected to further improve the wea…
Fatigue properties of commercial purity titanium sheets severely deformed by the accumulative roll bonding (ARB) process were investigated. The ARB process was carried out up to 6 cycles (equivalent strain, εeq.=4.8). The sheets ARB processed by 2-, 4- and 6-cycle consist of fine equiaxed grains and elongated lamellar…
Grain boundary structures of ultrafine grained pure copper (Cu) fabricated by the accumulative roll bonding (ARB) have been studied. The atomic structures of grain boundaries in the ARB processed Cu (ARB-Cu) were observed by high resolution electron microscopy. In order to compare the grain boundaries in the ARB-Cu wi…
Planar Guinier-Preston zones (GP-zones) parallel to a basal plane of an Mg hexagonal lattice are found together with β′ and β1 precipitates, which have been found in Mg-Gd alloys, in an Mg-2 at%Gd-1 at%Zn (Mg97Gd2Zn1) alloy aged at 200°C for 150 hrs. From the combination of high-resolution transmission electron micros…
The enhancement of toughness at low temperatures in fine grained low carbon steel was studied, basing on a shielding theory due to dislocations and grain boundaries. Fully annealed low carbon steel was subjected to an accumulative roll bonding (ARB) process for grain refining. The grain size perpendicular to the norma…
In order to estimate the strain energies of pure Cu and pure Al prepared by ECAP and ARB processes, dislocation densities remaining in these metals after each process were analyzed by the Warren-Abervach method based on the Williamson-Hall plot from a series of data taken by conventional X-ray diffractometry. The meas…
Copper is one of the most important materials used for electrical connectors with a high thermal and electricial conductivity, and there is an ongoing demand to improve its mechanical properties without sacrificing other beneficial properties. A possible approach to achieving this aim is to use the method of severe pl…
High purity Al (99.99%) is subjected to severe plastic deformation (SPD) at room temperature using a process of twist extrusion (TE). The microstructure evolution and the related change in microhardness are examined with respect to imposed strain. It is shown that subgrains develop after the first TE pass with a size…
SUS316L stainless steel and commercially pure titanium powders are processed by Mechanical Milling (MM) which is one of Severe Plastic Deformation (SPD) process. These MM powders are sintered by Hot Roll Sintering (HRS) process. Microstructure of materials produced by HRS process consists of a shell and core hybrid mi…
Ultrafine grained commercial purity titanium (CP-Ti) was fabricated by accumulative roll-bonding (ARB) process up to 6 cycles at ambient temperature. The microstructure was composed of the equiaxed grain structure having a mean grain size of 90 nm and the lamellar boundary structure having a mean lamellar spacing of 7…
A Zn-22% Al eutectoid alloy was processed by Equal-Channel Angular Processing (ECAP) to produce a grain size of ∼0.8 μm. Tensile testing at 473 K gave a maximum elongation of ∼2230% at a strain rate of 1.0×10−2 s−1. The significance of grain boundary sliding was evaluated by taking measurements of offsets in surface m…