Фазовая диаграмма системы Ag-V

К оглавлению: Другие диаграммы (Others phase diargams)

Ag-V (Silver-Vanadium) J.F. Smith The calculated Ag-V phase diagram is given for pressures sufficiently high to constrain all phases to condensed form. [15Gie] published a report of observations on a single Ag-V sample containing 77 at.% Ag, which indicated that no Ag was found in the upper, V-rich layer and no V was found in the lower, Ag-rich layer, but no mention is made in the report as to what techniques were used to establish the absence of Ag in V or of V in Ag. This indication of immiscibility in the Ag-V system is supported by later work of [54Ros], who used purer V. [54Ros] attempted to prepare four Ag-V alloys in the composition range 1.25 to 5 at.% Ag by arc melting under a helium atmosphere on a water-cooled copper hearth. All four alloys showed a weight loss corresponding to the Ag content, and chemical analyses failed to detect any Ag in the resultant ingots. This absence of Ag in the arc-melted material could have occurred because the kinetics of Ag volatilization were sufficiently rapid that insufficient time was available for the dissolution of any significant Ag by the V. Alternatively, if adequate time was available for the dissolution of an appreciable amount of Ag, the requisite decrease in Ag activity and attendant volatility associated with decreasing Ag concentration should have left a detectable Ag residue in the V solvent. In this situation, the absence of Ag in the V would imply limited to negligible solubility of Ag in V at the temperatures reached in the arc melter. Such restricted solubility seems the more likely of the two possible explanations of the experimental observations. 15Gie: H. Giebelhausen, Z. Anorg. Chem., 91, 251-263 (1915). 54Ros: W. Rostoker and A. Yamamoto, Trans. Am. Soc. Met., 46, 1136-1167 (1954). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 2 figures and 4 references. 1