Results 1 - 10 of 2197
Results 1 - 10 of 2197. Search took: 0.022 seconds
|Sort by: date | relevance|
[en] Phase diagrams serve as the fundamental guidance in materials science and engineering. Binary P-T-X (pressure–temperature–composition) and multi-component phase diagrams are of complex spatial geometry, which brings difficulty for understanding. The authors constructed 3D stereo binary P-T-X, typical ternary and some quaternary phase diagrams. A phase diagram construction algorithm based on the calculated phase reaction data in PandaT was developed. And the 3D stereo phase diagram of Al-Cu-Mg ternary system is presented. These phase diagrams can be illustrated by wireframe, surface, solid or their mixture, isotherms and isopleths can be generated. All of these can be displayed by the three typical display ways: electronic shutter, polarization and anaglyph (for example red-cyan glasses). Especially, they can be printed out with 3D stereo effect on paper, and watched by the aid of anaglyph glasses, which makes 3D stereo book of phase diagrams come to reality. Compared with the traditional illustration way, the front of phase diagrams protrude from the screen and the back stretches far behind of the screen under 3D stereo display, the spatial structure can be clearly and immediately perceived. These 3D stereo phase diagrams are useful in teaching and research. - Highlights: • Stereo 3D phase diagram database was constructed, including binary P-T-X, ternary, some quaternary and real ternary systems. • The phase diagrams can be watched by active shutter or polarized or anaglyph glasses. • The print phase diagrams retains 3D stereo effect which can be achieved by the aid of anaglyph glasses.
[en] Using a planetary ball mill and starting from a mixture of Mg2Ni and Ni with a Mg atomic content ranging from 40 to 60 at.%, we have elaborated amorphous phase alloys with little quantities of residual Ni. The synthesis of the amorphous phase proceeded at 6.49 W g-1 shock power, for milling durations ranging from 8 to 10 h for Mg40Ni60 and Mg60Ni40 samples, respectively. The best electrochemical capacity (470 mAh g-1, equivalent of MgNiH2.0) was obtained for the Mg50Ni50 sample synthesized in milling duration 10 times shorter than that commonly reported in the literature
[en] Highlights: • Mechanical alloying of Co62Nb6Zr2B30 leads to amorphous phase with B inclusions. • Using optimized amorphous B, amorphization occurs earlier. • B is more effectively introduced in the matrix using amorphous B. • Magnetoelasic contribution to effective magnetic anisotropy is negligible. -- Abstract: Co62Nb6Zr2B30 composition was mechanically alloyed using three different types of boron powders in the starting mixture: crystalline β-B, commercial amorphous B and optimized amorphous B via ball milling. Using optimized amorphous B, amorphization process of the alloy is more efficient but milling to optimize amorphous B introduces some iron contamination. Boron inclusions (100–150 nm in size) remain even after long milling times. However, using amorphous boron reduces the fraction of boron distributed as inclusions to ∼40% of the total B. Thermal stability at the end of the milling process is affected by the initial boron microstructure. Coercivity is reduced a half using amorphous B instead of crystalline B in the starting mixture
[en] Electronic spectral studies of lanthanides (Ln) in mixed metal environments of the type [Ln(III).DTPA.M(II)] (where Ln(III)=Pr, Nd, Sm, Dy, Er, Tm; and M(II)=Mn, Fe, Co, Ni, Cu and Zn) in aqueous phase at controlled pH (∝4.00) have been carried out in order to evaluate electronic spectral parameters, viz: (i) oscillator strength (fJO), (ii) Judd-Ofelt parameters (Tλ), (iii) interelectronic repulsion (Racah) parameters (δEk) and (iv) nephelauxetic ratio (δE3/δE1) values in mixed metal environments and to examine their variations as a result of insertion of M(II) (3d transition metal) ions in a [Ln.DTPA] environment. Octadentate DTPA has been used as a bridging ligand between two elemental moieties, viz: Ln(III) and M(II). The electronic spectral parameters (fJO), (Tλ) and (δE3/δE1) values show marked dependence on the nature of M(II) ions inserted in [Ln.DTPA] complex with a general sequence of Mn< Fe< Co< Ni< Cu>Zn indicating an allowed dependence of the spectral parameters on the nature of the M(II) ion. The variations in the spectral parameters have been discussed in light of partial covalency, symmetry around the Ln(III) cation and the degree of delocalisation of the 4f shell. J quantum number dependency of the electronic spectral parameters has also been discussed. (orig.)
[en] Highlights: •We use high – energetic planetary ball mill to activate Ni + Al powder mixtures. •Temperature of the reaction initiation decreases depending on the activation mode. •Nanocrystalline and amorphous phases, non-detectable by XRD, found by HR TEM. •Formation of the nano-structures are responsible for increasing reactivity. •A model explaining dependence of reactivity on microstructure is proposed. -- Abstract: Investigation of the micro- and atomic structures for the planetary ball-milled Ni + Al mixtures has revealed existence of intermediate nano-crystalline and amorphous phases, which are not detectable by XRD analysis, but can be observed by means of HRTEM. Annealing of the milled mixtures at moderate temperature, 205–280 °C, transforms the nano-phases into crystal state and makes them XRD-detectable. These nano-scale structures may serve as nucleus for the intermetallic phases produced via reaction between Ni and Al and, therefore, decrease the activation energy of this reaction and diminish the temperature of the reaction initiation. Apparently, the active nano-phases are formed due to sliding of Al and Ni layers during the ball milling. The simple model is suggested, which allows non-contradictory explanations of the nucleus formation and their influence on the reactivity of the mixture
[en] A new algorithm for the calculation of phase diagrams based on the method of convex hulls is presented. The computer program and database for thermodynamic modeling of binary systems are described and examples of calculated phase diagrams are given
[en] Highlights: • SmCo5−xFex alloys were produced by melt-spinning and subsequent annealing. • The Sm(Co,Fe)5 phase can be obtained up to x = 2 in SmCo5−xFex alloys. • The SmCo2Fe3 alloy consisted of very fine grains of the Sm(Co,Fe) 7 and Fe phases. • The SmCo2Fe3 nanocomposite magnet exhibited a high remanence of 100 emu/g. -- Abstract: SmCo5−xFex (x = 0–4) alloys were produced by melt-spinning and subsequent annealing. It was found that the small substitution of Fe for Co in the SmCo5 alloy results in the formation of the Sm(Co,Fe)5 phase, but that the large substitution of Fe for Co results in the formation of other phases such as the Sm(Co,Fe)7 and Sm2(Co,Fe)7 phases. The remanence of the annealed SmCo5−xFex melt-spun ribbons increased from x = 0 to x = 3 then decreased with increasing Fe content, while their coercivity decreased as the Fe content increased. Transmission electron microscope (TEM) studies revealed that the annealed SmCo4Fe melt-spun ribbon consisted of relatively coarse Sm(Co,Fe)5 grains, whereas the annealed SmCo2Fe3 melt-spun ribbon consisted of a mixture of extremely fine grains of the Sm(Co,Fe)7 and Fe phases. The annealed SmCo4Fe alloy with the Sm(Co,Fe)5 phase showed a high coercivity of 10.2 kOe with a remanence of 60 emu/g, while the annealed SmCo2Fe3 alloy formed a nanocomposite magnet with a high remanence of 100 emu/g and a coercivity of 2.9 kOe
[en] We report EXAFS (extended X-ray absorption fine structure) measurements on three solid solutions of rare-earth monotelluride in order to measure the x-dependence of the cation-anion distance and Debye-Waller factor. We find Yb1-xEuxTe is an ideal solid solution with a bimodal distribution of distances, accommodated by the Te sublattice, at contrast with the two other solid solutions Pb1-xEuxTe and Yb1-xGdxTe. The anomalous behaviour of the EXAFS parameters in the last system is related to the shallow nature of the Gd donor. (orig.)
[en] Raman Ln-Cl stretching spectra (Ln=rare earth ion) were measured for alcoholic solutions (alcohol=methanol, ethanol and n-propanol) of anhydrous rare earth chlorides. From the extended s-shaped variation of the frequency for the Ln-Cl stretching Raman band across the series, it is concluded that the inner-coordination number of rare earth ions decreases by one in the latter region of the rare earth series. (orig.)
[en] Highlights: ► Phase diagram of Fe–B–V system was modelled by CALPHAD method. ► Database for thermodynamic calculations for Fe–B–V system was created. ► The new ternary phase was found in 67Fe–18B–15V [in at.%] alloy. - Abstract: The phase equilibria of the Fe–B–V ternary system are studied experimentally and theoretically in this paper. Phase diagram of the system was modelled by CALPHAD method. Boron was modelled as an interstitial element in the FCC and BCC solid solutions. The calculations of isothermal sections of phase diagram are compared with our experimental results at 903 and 1353 K and with available literature experimental data. New ternary phase (with chemical composition 28Fe32V40B in at.%) was found in 67Fe–18B–15V alloy [in at.%]. Further experimental studies for the determination of exact nature of the ternary phase including crystallographic information are necessary.