β Scribed by V.G Rivlin; W Hume-Rothery; B Ryder
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The equilibrium diagram of the system Au-Cd has been investigated by thermal, microscopical, and X-ray diffraction m&hods. At high temperatures the phases present are (1) the cc solid solution of cadmium in gold, (2) the CL* phase which is of variable composition with close-packed hexagonal structure, and (3) the p body-centred cubic phase which remains highly ordered at a few degrees below the melting point. No evidence was found for the existence of the a? phase claimed by Owen et al. or of the a" phase postulated by Bystram and Almin, On the cadmium-nch side, the do; phase has a normal close-packed hexagonal sbructure but, in the range 27-34 at. o/0 Cd, highly faulted structures are observed, and a possible cause of this is suggested in terms of the curves of densities of electronic states. In the region of 25 at. y0 Cd, at low temperatures, a face-centred tetragonal phase is formed, and also a new face-centred cubic phase which has not been described before. CONSTITUTION ET STRUCTURE DES ALLIAGES OR-CADMIUM Les auteurs ont &udi6 le diagramme d'bquilibre du systbme Au-Cd, par analyse thermique, par micrographie et par diffraction des rayons X. Les phases presentes B haute temperature sont (1) la solution solide a de cadmium dans l'or (2) la phase cr, qui possede une structure hexagonale compacte et une composition variable et (3) la phase ,!I', cubique cent&e, qui reste hautement ordonnbe jusqu'8 quelques degr& du point de fusion. Les auteurs n'ont pas observe! la phase as signal& par Owen et al. ni la phase a" admise par Bystram et Almin. Dans le domaine riche en cadmium, la phase a, possede une structure hexagonale compacte normale, mais on observe dans le domaine 27-34 et-% Cd des structures avec une forte proportion de fontes d'empilement, dont l'explication pourrait 6tre trouvt?e dans les courbes de densite Blectronique. Dans le voisinage de 25 at-% Cd, une phase t&ragonale B faces cent&es se forme basse tempbrature, de mhme qu'une nouvelle phase cubique Q faces centrbes qui n'a pas encore BtB d&rite jusqu'8 p&sent.
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On the basis of electrical conductance and Raman-spectroscopic data, the assumption of CdC1,2m ions is upheld against a proposal of CdCl,-ions. R&sum&+-En d&accord avec les conclusions times par Bockris et Angel1 de mesures du coefficient de self-diffusion de l'ion Cd2+ dans les melanges fondus CdC
The growth of structural modulations during the early stages of precipitation in gold-platinum days has been investigated using the Debye-Scherrer S-ray diffraction method. Three alloys having the compositions 409; Pt-00% Au, BOD,: Pt-4@O,b Au, and 80c;io Pt-2Oq6 Au were examined over the aging temp