Фазовая диаграмма системы Pu-Ti

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Pu-Ti (Plutonium-Titanium) J.L. Murray The Ti-Pu system is characterized by the lack of intermetallic compounds. All investigators agree that melting occurs by the peritectic reaction L + (bTi) = (ePu), that there is a miscibility gap between the bcc (bTi) and (ePu) phases whose critical point lies above the peritectic temperature, and that there is a eutectoid reaction (bTi) = (aTi) + (ePu). Concerning the detailed placement of the phase boundaries and the invariant temperatures, the disagreements are significant. The discrepancies are exacerbated by the lack of detailed documentation of experimental procedures, which would allow a reasoned assessment to be made. The phase diagram must therefore be considered extremely uncertain. Experimental work has been reported by [60Poo], [61Ell], [ 65Kut], and [71Lan]. [61Ell] dealt only with the (dPu)/(d›Pu) equilibria. The others covered the entire composition range. [60Poo] investigated the diagram by thermal analysis, dilatometry, X-ray diffraction, and metallography. Alloys were arc melted. No further information was given on details of the experiments. [65Kut] reported data from thermal analysis and X-ray diffraction on Pu-rich alloys. [71Lan] used dilatometry, metallography, and chemical analysis of equilibrated two-phase alloys and of heat treated and quenched diffusion couples. Impurity levels in the Ti and Pu were 320 and 400 ppm, respectively. The (dPu)/(d›Pu) boundaries are based on [61Ell]. High-temperature X-ray diffraction was used to locate the invariant temperatures to about с2 C and the eutectoid composition to с0.25 at.%. [61Ell] is preferred to [65Kut], whose (ePu) = (d›Pu) + (aTi) reaction has not been verified. A metastable bcc (ePu) solid solution can be retained to room temperature by rapid solidification (106 to 108 C/s) [73Ell]. Alloys containing 55 to 80 at.% Pu had a single-phase bcc structure; alloys containing 80 to 100 at.% Pu had the fcc (dPu) structure and had probably transformed from (ePu) in the solid state. [65Kut] reported (dPu) phase retained in alloys that contained less than 73 at.% Pu that were quenched from the (ePu) region. [65Kut] also reported (bPu), (aPu), and a complex metastable phase in more dilute Pu alloys. The transformations (bTi) <259> (aTi) and (bPu) <259> (aPu) can occur by a martensitic mechanism [70Lan]. 60Poo: D.M.Poole, M.G. Bale, P.G. Mardon, J.A.C. Marples, and J.L. Nichols, Plutonium, E. Grison et al., Ed., 267-280 (1960). 61Ell: R.O. Elliott and A.C. Larson, The Metal Plutonium, A.S. Coffinberry and W.N. Miner, Ed., University of Chicago Press, Chicago, IL, 265-280 (1961). 65Kut: V.I. Kutaitsev, N.T. Chebotarev, I.G. Lebedev, M.A. Andrianov, V.N. Korve, and T.S. Menshikova, Plutonium 1965, Proc. Third Int. Conf. on Plutonium, London, 420-449 (1965). 70Lan: A. Languille, C. Remy, and C. Calais, J. Nucl. Mater., 37, 139-152 ( 1970). 71Lan: A. Languille, M‚m. Sci. Rev. M‚tall., 68(6), 435-441 (1971). 73Ell: R.O. Elliott and A.M. Russell, J. Mater. Sci., 8, 1325-1330 (1973). Published in Phase Diagrams of Binary Titanium Alloys, 1987. Complete evaluation contains 4 figures, 5 tables, and 9 references. Special Points of the Ti-Pu System