Фазовая диаграмма системы Ca-Ni

К оглавлению: Другие диаграммы (Others phase diargams)


Ca-Ni (Calcium-Nickel) H. Okamoto [65Tak] (also [66Tak]) proposed a phase diagram with two intermetallic phases<311> Ca2Ni5 and CaNi5<311>based on thermal, chemical, X-ray, and metallographic observations. Thermodynamic activity data of [76Dug] were consistent with this diagram. However, powder X-ray measurements by [74Bus] on sintered specimens with various compositions revealed four intermetallic phases CaNi2, CaNi3, Ca2Ni7, and CaNi5. [83Not] constructed a phase diagram including these four phases and thermal arrest data given by [65Tak]. CaNi5 melts peritectically [86Sai], rather than congruently [65Tak]. The assessed Ca-Ni diagram comprises the above information. The overall form of the assessed liquidus boundaries is based on [65Tak]. The L = (bCa) + CaNi2 eutectic temperature is 605 C. The L = CaNi5 + (Ni) eutectic point is 91 at.% Ni and 1160 с 10 C [65Tak]. If the solubility of Ca in (Ni) is negligible, the initial slope of the (Ni) liquidus must be -0.07 at. %/C according to van't Hoff's relationship. No solubility of Ni is known in either form of Ca. [65Tak] reported the hexagonal phase with the probable formula Ca2Ni5; the peritectic melting temperature is 1035 C. Vapor pressure data obtained by [ 76Dug] were consistent with the phase diagram of [65Tak], except for some solid solution formation on the Ca-rich side of the diagram. It is likely that the observation of [76Dug] suggests the presence of similar phases near Ca2Ni5. However, it is not clear whether Ca2Ni5 is independent of or related to the neighboring CaNi3 phase, which appears to have a similar crystal structure. CaNi3 and Ca2Ni7, having similar crystal structures, were found by [74Bus]. According to [83Not], the peritectic melting temperatures are 1157 and 1187 C, respectively. These temperatures were derived by extensive extrapolation of anomalous points in emf vs temperature plots. Further corroboration may be needed regarding both phase identifications and decomposition temperatures. CaNi5 was found by [42Now] and confirmed by [65Tak] and [74Bus]. The melting point of CaNi5 was estimated to be about 1230 C, based on metallographic analysis of variously heat-treated alloys [65Tak]. According to [86Sai], the type of melting is not congruent, as speculated by [65Tak], but peritectic, because no eutectic structures were found between CaNi5 and Ni. Editor's Note: DTA data are available in [90Not], who considered that CaNi5 melts congruently at 1205 C. 42Now: H. Nowotny, Z. Metallkd., 34, 247-253 (1942) in German. 65Tak: Y. Takeuchi, K. Mochizuki, M. Watanabe, and I. Obinata, J. Jpn. Inst. Met., 29(8), 806-810 (1965) in Japanese. 66Tak: Y. Takeuchi, K. Mochizuki, M. Watanabe, and I. Obinata, J. Jpn. Inst. Met., 29(8), 806-810 (1965) in Japanese. 68Bod: O.I. Bodak and E.I. Gladyshevskii, Dop. Akad. Nauk Ukr., RSR, 30(10), 944-947 (1968). 74Bus: K.H.J. Buschow, J. Less-Common Met., 38(1), 95-98 (1974). 76Dug: P.J. Dugdale, Dissertation, Univ. New Brunswick, Fredericton, NB, Canada (1976). 83Cha: M.W. Chase, Bull. Alloy Phase Diagrams, 4(1), 123-124 (1983). 83Not: M. Notin and J. Hertz, Acta Metall., 31(6), 903-908 (1983) in French. 86Sai: G. Saindrenan, J. Vitart-Barbier, and M. Constantinoff, J. Less-Common Met., 118, 227-233 (1986). 90Not: M. Notin, D. Beltacha, M. Rahmane, J. Hertz, G. Saindrenan, and J.L. Jorda, J. Less-Common Met., 162, 221-229 (1990). Published in Phase Diagrams of Binary Nickel Alloys, 1991.Complete evaluation contains 1 figure, 4 tables, and 14 references. 1