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Intermetallic chemistry
No full textThis book emphasizes the chemical aspects of the intermetallic science and therefore the mutual reactivity of metals and the characteristics of intermetallic compounds. Topics included are: Phase diagrams of alloy systems; Selected aspects of intermetallics structural chemistry with emphasis on the solid state; Intermetallic reactivity trends in the Periodic Table; Alloying behaviour systematics of intermetallic systems; Small scale preparation methods of intermetallic
Structure of intermetallic compounds and phases
No full textSolid state chemistry of intermetallic compound
Crystal structure of Nd3Au4 and Nd17Au36
No full textThe crystal structures of two phases in the neodymium-gold system were determined by single crystal X-ray diffractometer methods, '/.(MoKx = 0.7107 A. Nd3Au4(hR42) is trigonal, R3 (n. 148), a = 13.739(3) A, c = 6.088(2) A, Z = 6, R = 0.083 with 405 reflections, isotypic with Pu3,Pd4. Nd,7Au36(tP 106) is tetragonal, P4/nmm (n. 129), a = 15.835(4) A, c = 9.278(2) A, Z = 2, R = 0.082 with 540 reflections. The structure of Nd17Au36, which represents a new type, can be described as packing of bicapped square antiprisms with vertices occupied by five Nd and five Au atoms and centered by part of the gold atoms. This kind of polyhedron is identical to that of aluminium in the pyramidal site of the BaAl4 structure. In the Nd —Au system the phase Nd17Au36 replaces the phase given as “NdAu2”. © 1994, R. Oldenbourg Verlag. München. All rights reserved
Phase equilibria in the Pr-Tl system
No full textThe Pr-Tl system was studied in the composition range 15-100 at.% Tl using differential thermal analysis, metallography and X-ray examination. The praseodymium-rich alloys were reinvestigated and the published phase diagram was confirmed. The following intermetallic compounds were observed: Pr3Tl (decomposes at 800 ± 10 °C); Pr2Tl (decomposes at 940 ± 10 °C); Pr5Tl3 (decomposes at 1020 ± 10 °C); PrTl (melting point, 1260 ± 10 °C); Pr3Tl5 (melting point, 1120 ± 10 °C); PrTl3 (melting point, 1065 ± 10 °C). Four eutectics occur: β-Pr-Pr3Tl (767 ± 1 °C, 13.9 ± 0.1 at.% Tl); PrTl-Pr3Tl5 (1090 ± 10 °C, 58.0 ± 0.5 at.% Tl); Pr3Tl5-PrTl3 (1035 ± 10 °C, 69.0 ± 0.5 at.% Tl); PrTl3-β-Tl (303 °C, greater than 99.5 at.% Tl). β-Pr decomposes eutectoidally at 687 ± 1 °C and 8.0 ± 0.2 at.% Tl. The crystal structures of Pr3Tl (ordered-disordered cP4 AuCu3 and cF4 Cu types), Pr5Tl3 (tI32 W5Si3 type), PrTl (cP2 CsCl type) and PrTl3 (cP4 AuCu3 type) were confirmed. Pr3Tl5 was found to have an orthorhombic oC32 Pu3Pd5 type of structure. The characteristics of the phase diagram and the molar volumes of the Pr-Tl alloys are compared with those of the Ce-Tl and Nd-Tl systems. © 1981
The 400 °C Isothermal Section of the La-Co-Mg Ternary System
No full textThe isothermal section of the La-Co-Mg system at 400 °C was determined by characterization of about thirty ternary alloys synthesised by induction melting in sealed Ta crucibles and then annealed. Scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDXS) and x-ray powder diffraction (XRPD) were used to analyze microstructures, identify phases, measure their compositions and determine their crystal structures. Phase equilibria are characterized by the absence of ternary solid solutions and by the presence of three ternary phases. The existence and the crystal structure of the La4-xCoMg1 + x (τ1, 0 ≤ x ≤0.15, cF96-Gd4RhIn) were confirmed and its homogeneity region determined; the new phases La23-xCo7Mg4 + x (τ2, -0.50≤ x ≤0.60, hP68-Pr23Ir7Mg4) and ~La38Co55Mg7 (τ3, unknown crystal structure) were detecte
Phase relationships of the R-Al-Si systems: The Pr-Al-Si isothermal section at 500 °c
No full textIn the framework of a systematic investigation of intermetallic systems, constituted by aluminium and silicon with a rare earth metal, the isothermal section at 500 °C of the Pr-Al-Si system has been experimentally investigated. The experimental techniques used were scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction, and some samples have been analysed by differential thermal analysis. The existence of six ternary compounds has been confirmed, one of them showing a composition homogeneity range: τ1 PrAl2Si2 (hP5-Ce2SO2 type), τ2 Pr3Al4Si6 (hP13-Ce3Al4Si6 type), τ3 PrAlSi2 (hP8-CeAlSi2 type), τ4 Pr2Al3Si (hP3-AlB2 type), τ5 PrAl(1-x)Si(1+x) (tI12-αThSi2Si type) and τ6 Pr2AlSi (oS8-CrB type). A few compounds pertaining to the binary boundary systems Pr-Al and Pr-Si dissolve the third elemen
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