Фазовая диаграмма системы Hf-Ti

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Hf-Ti (Hafnium-Thorium) J.L. Murray Ti and Hf are completely miscible in both (aTi,aHf) and (bTi,bHf). The present assessment does not differ significantly from that given by [Hansen]. The assessed phase diagram was obtained by least-squares optimization of select experimental data. Calculation of the diagram has improved the accuracy of the width of the two-phase regions. Liquidus and solidus data of [57Hay], [66Cha], and [69Rud] agree within the experimental uncertainty. [69Rud] reported congruent melting over a large compostion range (0 to 40 at.% Hf) and a narrow two-phase region at higher Hf concentrations. The data of [57Hay] imply a wider two-phase region. [72Rud] reported different temperatures for the beginning and end of the (aTi, aHf)/(bTi,bHf) transformation depending on the experimental probe. The differential thermal analysis data of these authors are preferred over resistivity and dilatometric measurements as most likely to represent equilibrium, and they agree well with [57Hay],[62Img], and [66Cha]. No experimental studyof metastable phase formation in Ti-Hf alloys is presently available. The behavior of Ti-Hf alloys is likely to be similar to that of Ti-Zr alloys 57Hay: T. Hayes and D.K. Deardorff, U.S. At. Energy Comm. USBM-V-345 (1957). 62Img: A.G. Imgram, D.N. Williams, and H.R. Ogden, J. Less-Common Met., 4, 217-225 (1962). 66Cha: Y.A. Chang, USAF Tech. Rep. AFML-TR-65-2, Part II, Vol. V (1966). 69Rud: E. Rudy, USAF Tech. Rep. AFML-TR-65-2, Part V (1969). 72Rud: E. Rudy, USAF Tech. Rep. AFML-TR-65-2, Part VIII (1972). Published in Phase Diagrams of Binary Titanium Alloys, 1987, and Bull. Alloy Phase Diagrams, 2(2), Sep 1981. Complete evaluation contains 4 figures, 5 tables, and 8 references. Special Points of the Ti-Hf System