| 1. |
- Ahmed, Istaq, 1972, et al.
(författare)
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Location of deuteron sites in the proton conducting perovskite BaZr0.50In0.50O3-y
- 2008
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 450:1-2, s. 103-110
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution neutron powder diffraction data have been collected on deuterated and dried samples of the perovskite BaZr0.5In0.5O2.75 at 5 K and room temperature, respectively. Inspection of Fourier nuclear density maps for the deuterated phase have allowed the deuteron position to be refined on a 12h (1/2, y, 0) crystallographic site, with y = 0.217(4) yielding a chemically reasonable O-D distance of 0.92(2) angstrom. Evidence for anisotropy of the deuteron position is also found consistent with a 24k crystallographic site (0.56, 0.21, 0) indicative of displacements of the ion towards neighbouring oxygen ions. The presence of static oxygen disorder in both the dried and deuterated samples is apparent from the structural analyses. Raman spectra confirm short range deviations from cubic symmetry for both dried and hydrated samples.
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| 2. |
- Ahuja, B. L., et al.
(författare)
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A study of electron momentum density and charge transfer in W-Cu system
- 2009
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 467:1-2, s. 595-599
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Tidskriftsartikel (refereegranskat)abstract
- We present the first ever Compton scattering study on WxCu1-x(x=0.60, 0.72) alloys. The Compton profile measurements have been made using 20Ci (CS)-C-137 gamma-ray source. The experimental data are compared with the superposition of APW-based Compton profiles of constituent metals. A schematic study on charge transfer has been reported using the experimental valence band Compton profiles of both the alloys, W and Cu. Our first ever data support the charge transfer from W to Cu on alloying, which is also confirmed by our band structure calculations employing exact muffin-tin orbitals method (EMTO). (C) 2007 Elsevier B.V. All rights reserved.
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| 3. |
- Akhtar, Farid
(författare)
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Microstructure evolution and wear properties of in situ synthesized TiB 2 and TiC reinforced steel matrix composites
- 2008
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 459:1-2, s. 491-497
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Tidskriftsartikel (refereegranskat)abstract
- Steel matrix composite reinforced with TiB2 and TiC reinforcements (30 to 70wt%) have been produced through the synthesis reaction from Ti, C and FeB. The sintered composites were characterized by X-ray diffraction and scanning electron microscopy. TiB2, TiC and steel were detected by X-ray diffraction analysis. The scanning electron micrographs revealed the morphology and distribution of the reinforcements. TiB2 and TiC were thermally stable in the steel matrix. The results showed that different mechanisms of evolution of reinforcements in steel matrix were operative. TiB2 grew in hexagonal prismatic or rectangular shape and TiC in spherical shape. The reciprocating sliding wear test was conducted on the composite. The results of sliding wear showed that the wear loss decreased with increase in the reinforcement content. The wear mechanisms were polishing wear and microploughing for the composites containing high volume fraction of the reinforcements, whereas microploughing and grooving were the dominant wear mechanisms for the composites containing low volume fraction of the reinforcements.
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| 4. |
- Akhtar, Farid, et al.
(författare)
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Processing, microstructure and mechanical properties of TiC-465 stainless steel/465 stainless steel layer composites
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 439:1-2, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- Layered composites of carbide reinforcements and stainless steel have been prepared successfully by powder technology. The layer material consisted of two layers. Top layer consisted of reinforcements (TiC and NbC) and 465 stainless steel as binder material for carbides. The substrate material was of binder material (465 stainless steel). The microstructure of the composite was characterized by scanning electron microscopy. The microstructural study revealed that top layer (TiC-NbC/465 stainless steel) showed the typical core-rim microstructure of conventional steel bonded cermets and the substrate material showed the structure of sintered steel. An intermediate layer was formed due to diffusion reaction of top layer and substrate material. This intermediate layer showed a gradient microstructure. The bending strength of layered material measured in the direction perpendicular to the layer alignment was remarkably higher. Nineteen percent increase in bending strength in case of 53 wt% reinforcement in top layer and 35% increase in case of 73 wt% reinforcement in top layer was found. The variation of strength as a function of thickness of substrate material revealed that the character of material changed from cermet to a layer composite and then towards metallic materials. The fracture morphologies of top layer, substrate material and intermediate layer are also reported
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| 5. |
- Alami, J., et al.
(författare)
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High power pulsed magnetron sputtering : Fundamentals and applications
- 2009
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 483:1-2, s. 530-534
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Tidskriftsartikel (refereegranskat)abstract
- Direct current magnetron sputtering (dcMS) is a widely used technique for deposition of a large number of compound and metallic coatings with specified mechanical, electrical and optical properties. Although dcMS is a successful coating technique, it suffers from fundamental problems, such as low target utilization and target poisoning during reactive sputtering, which results in process instabilities and poor deposition rates. In order to alleviate some of these problems, alternative techniques, such as radio frequency magnetron sputtering, additional ionization by rf coils or microwaves, or increased magnetic confinement by a multipolar magnetic setup are used. High power unipolar pulsing of the target voltage is another approach that has been used of late, in order to increase the ionization fraction in the discharge. in this deposition technique, known as high power pulsed magnetron sputtering (HPPMS), the power supply operates at low (or zero) power level and pulses to a high voltage for a short time each cycle. Thus, high electron densities are generated leading to increased ionization of the sputtered material. With peak power densities typically of several kW cm(-2), ionization fractions of the sputtered material ranging from 4.5% for C to 70% for Cu are achieved. HPPMS has been used to grow metallic and compound coatings. In the present work, a summary over some of the important results related to this technique are presented. The mechanisms taking place in the discharge and at the coating surface during deposition are discussed and the benefits of using HPPMS are reviewed: tailoring of coating properties, control of the coating bombardment during deposition, enhancement of the coating mechanical properties and morphology. Finally, TiAlN coatings are deposited using an industrial coater, and the coatings properties are studied.
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| 6. |
- Andersson, Cristina, 1969, et al.
(författare)
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Tensile properties and microstructural characterization of Sn-0.7Cu-0.4Co bulk solder alloy for electronics applications
- 2008
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 457:1/2, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- The ternary Sn–Cu–Co system eutectic composition was obtained by means of CALPHAD (CALculation of PHAse Diagram) methodology and it was found to be 0.4% Co and 0.7% Cu (wt%) with a melting point of 224 ◦C. The tensile behavior of this alloy was investigated at different strain rates (10−5, 10−4 and 10−3 s−1) and compared to both Sn–37Pb and Sn–4.0Ag–0.5Cu. The Sn–4.0Ag–0.5Cu alloy depicts the highest ultimate tensile strength (UTS) followed by the Sn–37P and finally the Sn–0.7Cu–0.4Co system. The elastic modulus was also higher for the Sn–4.0Ag–0.5Cu followed by the Sn–0.7Cu–0.4Co and last the Sn–37Pb. The microstructure of the Sn–0.7Cu–0.4Co alloy is composed of two types of intermetallic phases, (Cu,Co)6Sn5 and (Co,Cu)Sn2 dispersed in a Sn-rich matrix. The microstructure of this alloy proved to be very stable, after aging at 150 °C for 24 h. The eutectic Sn–0.7Cu–0.4Co solder alloy can therefore be a very good alternative for theSACalloys for surface mount technology applications.
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| 7. |
- Araujo, Carlos Moyses, et al.
(författare)
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Electronic and optical properties of pressure induced phases of MgH2
- 2005
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Ingår i: Journal of Alloys and Compounds. - 0925-8388. ; 404:16, s. 220-
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Tidskriftsartikel (refereegranskat)abstract
- The electronic and optical properties of pressure-induced phases of MgH2 are investigated using the full-potential linearized augmented plane wave method. The absorption features are investigated by means of the calculated complex dielectric function and the analysis are made based on the electronic structure. The phases as a whole exhibit a color neutral insulator behavior. The calculated band gap are in good agreement with earlier theoretical investigations. The absorption edges corrected by scissor operation matched quite well the experimental findings. The optical anisotropy has also been evaluated.
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| 8. |
- Baranovskiy, A. E., et al.
(författare)
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Electronic structure, bulk and magnetic properties of MB6 and MB12 borides
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 442:1-2, s. 228-230
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Tidskriftsartikel (refereegranskat)abstract
- The bulk and magnetic properties of MB6 and MB12 were investigated on the basis of first principles electronic structure calculations. The elastic constants were measured for ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 compounds at low temperatures. The calculated equations of states and balanced crystal orbital overlap populations have allowed to analyse bonding and magnetic properties of MB6 and MB12 .
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| 9. |
- Cao, Xiaohua, et al.
(författare)
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Nanoscale indentation behavior of pseudo-elastic Ti-Ni thin films
- 2008
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 465:1-2, s. 491-496
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Tidskriftsartikel (refereegranskat)abstract
- 48.28 at.%Ti-51.72 at.%Ni thin films were prepared by magnetron sputtering and post-annealed at 450, 500, 550 and 600 degrees C, respectively. The evolution of structure, phase transformation and nanoscale indentation behavior of Ti-Ni thin film annealed at different temperature were investigated by X-ray diffractometer (XRD), differential scanning calorimetry (DSC) and nanoindention test, respectively. The results showed that the as-deposited Ti-Ni thin films were amorphous and crystallized after post-annealing. As the annealing temperature increased from 450 to 600 degrees C, both the content of parent phase (B2) and that of the precipitate phase (Ni4Ti3) increased. Both the phase transformation temperature and the micro-hardness of the annealed Ti-Ni thin films increased as well. Meanwhile, the pseudo-elasticity energy recovery ratio 77 first increased to the maximum value and then decreased with the increasing annealing temperature. It revealed that the annealed Ti-Ni thin film specimens exhibited the highest pseudo-elasticity degree with the largest 71 values under the load of 10 mN.
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| 10. |
- Denys, R. V., et al.
(författare)
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Hydrogen storage properties and structure of La1-xMgx(Ni1-yMny)(3) intermetallics and their hydrides
- 2007
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 446, s. 166-172
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Tidskriftsartikel (refereegranskat)abstract
- 'Hybrid' RNi3 (R =rare earth metal) crystal structures are built of the slabs of simpler types, CaCu5 and MgZn2. Different affinities of these slabs to hydrogen result in unusual "anisotropic" expansion of the RNi3 and R2Ni7 (R = La, Cc) structures upon hydrogenation. This work focuses on studies of the hydrogenation behaviour of LaNi3 and on the properties of the hydrides of the modified by Mg and Mn La-Ni alloys. The crystal structure of LaNi3D2.8 and the crystal structure and hydrogen storage behaviours of the La1.5Mg0.5Ni7 and La(Ni-1-,Mn,)3 (x=0; 0.067-, 0.133; 0.2: 0.267; 0.3; 0.333; 0.4) alloys were in focus. The deuteration of LaNi3 with PuNi3 type of structure leads to the formation of LaNi3D2.8 and is accompanied by a deformation of the metal matrix causing a change of the initial rhombohedral symmetry (space group R3m) to a nionoclinic one (space group C2/m; a = 8.6408(7) angstrom, b=4.928](4) angstrom, c= 32.774(3) A; = 90.850(8)degrees; V= 1395.5(2) angstrom(3)). Similar to the earlier studied CeNi3D2.8, preferential occupation by deuterium atoms of the AB, layers takes place, leading to the "anisotropic" expansion of the unit cell along [0 0 1] (Delta c/c = 30.6%). 14 occupied D crystallographic sites have 4 chemically different types of metal-atom surroundings, including Ni-4 (2), La2Ni2 (2), La3Ni (6), and La3Ni3 (4). Modification of the La-Ni alloys by magnesium and manganese leads to the formation of intermetallic compounds crystallising with the PuNi3, CeNi3, and Ce2Ni7-type structures. An ordered substitution of La by Mg in the MgZn2-type slabs was observed, causing a complete alteration of the hydrogenation behaviour of the original LaNi3 alloy. La1.5Mg0.5Ni7D9 isotropically expands upon its formation and leads to a substantial increase of the stability against hydrogenation-induced aniorphisation. On the other hand, replacement of Ni by Mn leads to the change in crystal-structure type from PuNi3 to CeNi3 in the LaNi3-xMn. alloys (x>0.1). An ordered substitution of Ni by Mn proceeds inside the RNi5 slabs only. This decreases the stability of the initial alloy against amorphisation on hydrogenation.
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