- Hydrogen absorption in the Zr-Al system
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A series of Zr-Al alloys has been prepared and the reaction with hydrogen studied by microbalance thermogravimetric analysis and differential thermal analysis. Their geometric and electronic structures have been studied by X-ray powder diffraction, X-ray
- Clark, N. J.,Wu, E.
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- Effect of zirconium on thermal stability of nanocrystalline aluminium alloy prepared by mechanical alloying
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In the present study, a series of Al-x% Zr (x?=?1–10?at.%) compositions were prepared by mechanical alloying (MA) to investigate the solid solubility extension of Zr in Al and its thermal stability. The elemental powder blends were mechanically alloyed under high purity argon atmosphere in stainless steel grinding media using SPEX 8000?M high energy ball mill. The milling was carried out for 8?h?at room temperature and the ball to powder ratio was maintained at 10:1. Formation of disordered solid solutions is validated using Miedema's semi-empirical model. X-ray diffraction (XRD) analysis confirms the formation of disordered solid solution up to 1at.% Zr; whereas, Al3Zr and Al9.83Zr0.17intermetallic phases were found to form as per the XRD pattern of 2–10% Zr alloys. Variation of lattice parameter confirmed the formation of Al-1% Zr solid solution. Crystallite size was estimated to be 41 and 30?nm, respectively, for the as-milled 1 and 10% Zr alloys. The matrix grains were found to be stabilized after annealing at 550?°C, and the XRD crystallite size of Al-10% Zr retained at ~58?nm. TEM and AFM analysis confirmed that the grain size of the as-milled as well as annealed samples was retained in the nanometre range (a larger strengthening effect and Zr plausibly played a pivotal role in retaining the matrix grains size in the nanoscale range at high temperature.
- Muthaiah, V.M. Suntharavel,Mula, Suhrit
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- Phase equilibria in the ternary Al-Zr-La system
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The phase relationships in the Al-Zr-La ternary system at 773 K have been investigated for the first time mainly by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive analysis (EDX). The existenc
- Peng, Dan,Zhan, Yongzhong,She, Jia,Pang, Mingjun,Du, Yong
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- Zr4Al3D2.68 and Zr3Al2D2.26: New Zr-containing intermetallic hydrides with ordered hydrogen sublattice
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Two hydrogenated intermetallics with the highest Al/Zr ratio among the hydrogen-absorbing Zr-Al compounds, Zr4Al3 and Zr3Al2, have been studied by synchrotron X-ray, powder neutron diffraction and thermal desorption spectroscopy. Initial intermetallic compounds are quite different with respect to Al-Al interactions and contain plain Kagome Al nets (Zr4Al3) or Al-Al pairs (Zr3Al2). In hexagonal Zr4Al3D2.68 (space group (s.g.) P6322; a = 11.0017(4); c = 11.1694(5) ?) a 2a×2a×2c superstructure is formed as a result of deuterium ordering in half of the available Zr4 tetrahedra. These tetrahedra share common corners and edges and form layers separated by 6363 Al-nets. In tetragonal Zr3Al2D2.26 (s.g. P42/mnm; a = 7.5970(3); c = 7.2613(3) ?) in addition to the completely filled Zr4 tetrahedra hydrogen partially occupies Zr3 triangular sites. Thermal stability of the studied deuterides and Zr-D bonding characteristics can be related to the size of the occupied Zr4 tetrahedra. Higher thermal stability of Zr3Al2D2.26 agrees well with the existence of large Zr4 sites and contrasts to the behavior of Zr4Al3D2.68 containing 'contracted' Zr4 tetrahedra and having weaker Zr-D bonds.
- Riabov,Yartys,Denys,Hauback
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- HIGH-TEMPERATURE OXIDATION OF ZrAl.
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The oxidation of ZrAl in dry oxygen in the temperature range 800 - 1100 K follows a parabolic rate law. An activation energy of 86. 4 kJ mol** minus **1 was estimated. During the oxidation, aluminum diffuses from the oxide layer to the ZrAl bulk, thus forming a ZrAl//2 phase very close to the oxide-alloy interface. The excess zirconium is therefore selectively oxidized, yielding tetragonal mainly and monoclinic ZrO//2 containing no Al//2O//3.
- Paljevic M.
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p. 107 - 112
(2008/10/08)
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