Фазовая диаграмма системы Mn-Zn

К оглавлению: Другие диаграммы (Others phase diargams)

Mn-Zn (Manganese-Zinc) H. Okamoto and L.E. Tanner The assessed Mn-Zn phase diagram is based primarily on [67Wac] for the composition range 60 to 100 at.% Zn, on [71Rom] for 0 to 60 at.% Zn, and on [ 72Nak] for 30 to 70 at.% Zn below ~400 C. The most significant differences between the assessed diagram and the diagram of [Hansen], which is based primarily on [40Sch] and [49Pot], are (1) the presence of three related phase fields, e, e1, and e2 [67Wac], instead of only one wide field [Hansen]; (2) a continuous phase field between (dMn) and b [71Rom]; and (3) two low- temperature phases, b1 [72Nak] and a1› [62Nak2]. Because of disagreements in various reports and the lack of confirmatory work, many parts of the assessed diagram should be considered tentative or qualitative. The most ambiguous portion is the e phase fields. The liquidus observed by [67Wac] shows an unusual change of slope at ~830 C. To be continuous with the Mn-rich part of the liquidus, the results of [40Sch] and [71Rom] are accepted tentatively in the assessed diagram for the composition range >60 at.% Zn. [71Rom] showed that (dMn) and b are continuous, as shown in the assessed diagram. b is ordered CsCl-type [62Nak2], and there is no essential difference between b and b1 [64Nak]. Therefore, there may be an order-disorder transition between (dMn) and b, but no information to that effect is available. According to [49Pot], (gMn) has much wider temperature and composition ranges ( see [Hansen]). When quenched from the fcc (gMn) phase field, alloys with less than 19.5 at.% Zn transform to a metastable tetragonal phase (gMn1) at room temperature [49Pot, 51Zwi]. The (gMn) = (gMn1) metastable transition is likely to occur at the N‚el temperature of (gMn). The maximum solubility of Zn in (bMn) is 48 at.% [72Nak]. The (bMn)/[(bMn) + b1] boundary below 150 C shown by [72Nak] is a vertical line at 40 at.% Zn. The assessed boundary is drawn differently, assuming a continuous change of curvature. The (bMn)/[(bMn) + (aMn)] boundary as determined by [49Pot] and [71Rom] is 16 с 1 at.% at 400 C. The assessed diagram is an approximate average of the two. The maximum solubility of Zn in (aMn) is about 1.7 at.% [49Pot]. The e phase fields are controversial, and the three variants in the assessed diagram should be regarded as tentative. e was found by [30Par], [31Par], [ 32Par], and [36Par], although the phase relationships were not clarified. [ 40Sch] found a wide e phase field covering 42 to 88 at.% Zn. [67Wac] proposed that e consists of three strongly similar regions as shown in the assessed diagram, but a further investigation by [71Rom] revealed no subdivisions. [ 60Tez] and [64Nak] found Ni3Sn-type, metastable e› in a 73 at.% Zn alloy, as a transition phase from e to a›. [62Nak2] found the same metastable phase in a 75 at.% Zn alloy annealed at about 100 C. Although considered obsolete by [Hansen] (correctly, concerning the identification of solid phases in equilibrium with L), earlier investigators found several peritectic reactions in the e range that might be related to the peritectics of e1 and e2 in the assessed diagram: 730 and 585 C [15Par]; 570 and 510 C [19Gie]; and 618 and 560 C [27Ack]. These temperatures do not agree well. The changes of lattice parameters with composition measured by [64Hen] and [ 70Far] in an approximate composition range between 45 and 85 at.% Zn showed no anomalies at the possible boundaries between e phases, indicating no phase separations. However, because of their quite different composition dependence, it is possible that there is more than one state in the e range. e› tentatively is identified as e1 in this evaluation. Further studies on the equilibrium diagram are needed. The a› phase boundaries in the assessed diagram are almost as proposed by [ 40Sch]. The Mn-rich limit is 70 at.% Zn at 150 and 100 C [72Nak]. The a› <259> a1› transition at about -143 C [69Uch] is probably caused by the Jahn-Tellar effect [62Nak2] and is similar to the fcc <259> fct transition in (gMn) [69Uch] . According to earlier determinations, the solubility of Mn in (Zn) is 0.58 [ 40Sch] or 0.53 [48Rod] at.% at the eutectic temperature and <0.02 at.% at 200 C [48Rod]. [70Far] found that the solubility is more than 1.2 at.% Mn at 400 C. The van't Hoff relationship indicates only that Mn solubility at the eutectic temperature is between the two values given by [40Sch] and [70Far]. Solubility of 1 at.% Mn is assumed in the assessed diagram. There are several magnetic phases in the Mn-Zn system. [50Now] first observed that a 70 at.% Zn alloy quenched from a high temperature is ferromagnetic. According to [60Tez], it is e1, with a Curie temperature (TC) higher than 127 C. [60Tez] also found that a› becomes antiferromagnetic below 140 K. The transition temperature was revised to 100 K [62Nak2], -120 C (153 K) [62Nak1], then to 130 K [69Uch]. Because the metastable transition of fcc (gMn) <259> (gMn1) corresponds to the onset of antiferromagnetism, the N‚el temperature of (gMn) is room temperature at about 20 at.% Zn. The TC of g is 70 K [62Nak2]. The TC of b1 is higher than 277 C [64Hor]. The magnetic structure of b1 was clarified by [68Hor]. The composition and temperature dependence of magnetic susceptibility of Zn-rich (> 60 at.%) liquid and solid alloys was measured in detail by [67Wac]. 15Par: N. Parravano and U. Perret, Gass. Chim. Ital., 45(1), 1-6 (1915) in Italian. 19Gie: P. Gieren, Z. Metallkd., 11, 14-22 (1919) in German. 27Ack: C.L. Ackermann, Z. Metallkd., 19(5), 200-204 (1927) in German. 30Par: N. Parravano and V. Montoro, Mem. Accad. Ital. Sci. Fis. Mat. Nat., Chim., 1(4), 19 p (1930); Met. Ital., 22, 1043-1051 (1930) in Italian. 31Par: N. Parravano and V. Caglioti, Rend. Accad. Nazl. Lincei, 14, 166-169 ( 1931) in Italian. 32Par: N. Parravano and V. Caglioti, Mem. Accad. Ital., Sci. Fis. Mat. Nat., Chim., 3(3), 5-21 (1932) in Italian. 36Par: N. Parravano and V. Caglioti, Ricerca Sci., 7, 223-224 (1936) in Italian. 40Sch: J. Schramm, Z. Metallkd., 32(12), 399-407 (1940) in German. 43Moe: K. Moeller, Z. Metallkd., 35(1), 27-28 (1943) in German. 48Rod: J.L. Rodda, unpublished work; Metals Handbook, 1948 ed., American Society for Metals, Cleveland, 1229 (1948). 49Pot: E.V. Potter and R.W. Huber, Trans. ASM, 41, 1001-1022 (1949). 50Now: H. Nowotny and H. Bittner, Monatsh. Chem., 81, 898-901 (1950) in German. 51Zwi: U. Zwicker, Z. Metallkd., 42, 246-252 (1951) in German. 60Tez: S. Tezuka, S. Sakai, and Y. Nakagawa, J. Phys. Soc. Jpn., 15, 931 (1960) . 62Bro: P.J. Brown, Acta Crystallogr., 15(6), 608-612 (1962). 62Nak1: Y. Nakagawa and T. Hori, J. Phys. Soc. Jpn., 17(8), 1313-1314 (1962). 62Nak2: Y. Nakagawa, S. Sakai, and T. Hori, J. Phys. Soc. Jpn., 17, Suppl. B-I, 168-171 (1962). 64Hen: B. Henderson and R.J.M. Willcox, Philos. Mag., 9(101), 829-846 (1964). 64Hor: T. Hori and Y. Nakagawa, J. Phys. Soc. Jpn., 19, 1255 (1964). 64Nak: Y. Nakagawa and T. Hori, J. Phys. Soc. Jpn., 19, 2082-2087 (1964). 67Wac: E. Wachtel and K. Tsiuplakis, Z. Metallkd., 58(1), 41-45 (1967). 68Hor: T. Hori, Y. Nakagawa, and J. Sakurai, J. Phys. Soc. Jpn., 24(5), 971- 976 (1968). 69Uch: H. Uchishiba, T. Hori, and Y. Nakagawa, J. Phys. Soc. Jpn., 27(3), 600- 604 (1969). 70Far: R.A. Farrar and H.W. King, Metallography, 3(1), 61-70 (1970). 71Rom: O. Romer and E. Wachtel, Z. Metallkd., 62(11), 820-825 (1971) in German. 72Nak: Y. Nakagawa and T. Hori, Trans. Jpn. Inst. Met., 13(3), 167-170 (1972). Published in Bull. Alloy Phase Diagrams, 11(4), Aug 1990. Complete evaluation contains 5 figures, 5 tables, and 38 references. Special Points of the Mn-Zn System