Фазовая диаграмма системы Cu-Pd

К оглавлению: Другие диаграммы (Others phase diargams)

Cu-Pd (Copper-Palladium) P.R. Subramanian and D.E. Laughlin The present evaluation of the Cu-Pd system updates the phase diagram of [ Hansen]. The assessed liquidus and solidus are based on the data of [06Rue] and [49Nem], with modifications in the temperatures so that the melting points of Cu and Pd conform to the accepted values of 1084.87 and 1555 C, respectively, from [Melt]. The equilibrium phases in the Cu-Pd system are (1) the liquid, L; (2) the fcc continuous solid solution, (Cu,Pd); (3) the ordered phase Cu3Pd, occurring in the solid solution phase field with a composition range of homogeneity; and (4) the ordered phase CuPd, also existing in the solid solution phase field with a range of homogeneity. The ordered phase Cu3Pd forms with the Cu3Au-type structure over the entire composition range 10 to 25 at.% Pd [34Tay]. [34Tay] observed the maximum transformation temperature at 500 C and at the off-stoichiometric composition of 15 at.% Pd. [39Jon] observed that the Cu3Au type of ordering is present only in alloys with less than ~20 at.% Pd. For alloys containing 20 to 25 at.% Pd, a tetragonal structure was observed. [39Jon] proposed the Cu3Pd phase boundaries as accepted in [Hansen] on the basis of the transformation data of [ 34Tay] in combination with their own resistivity and X-ray data. [55Sch] proposed the existence of one-dimensional antiphase domain (1D-APD) structure (or long-period superlattice, LPS) in alloys containing 18.5 to 25 at.% Pd and a "complex" APD structure in 25.5 to 30 at.% Pd alloys. Subsequently, [56Wat] determined the structure of alloys with 18 to ~28 at.% Pd (a›› phase). They observed that in alloys containing ~18 to 25 at.% Pd, the lattice consists of fct cells built in terms of the original disordered fcc cell. Moreover, the splitting of superlattice reflections indicated the presence of one-dimensional APD's with a periodicity of 2M3 along the tetragonal axis of the fct cell, where M3 is the half-period and varies with Pd content. In alloys with ~25 to 28 at.% Pd, the reflections indicated a two- dimensional APD structure, whereas the atoms have two kinds of step-shifts occurring at every M3th and M1th atom along the z- and x-directions, respectively, where M3 and M1 are the half periods in the two directions. [49Nem] proposed the existence of ordered structures corresponding to the stoichiometries Cu5Pd (16.67 at.% Pd) and Cu5Pd3 (37.5 at.% Pd). [34Tay] determined that the transformation from disordered (Cu,Pd) solid solution to ordered CuPd occurs over the range 35 to 50 at.% Pd. [34Tay] noted that the CuPd phase boundary shows a maximum at 596 C and that it occurs at the off-stoichiometric composition of 40 at.% Pd. The existence of this maximum was subsequently confirmed by [39Jon]. [81Iwa] studies the effect of pressure on the CuPd phase field and observed that the application of pressure displaced the CuPd phase field toward the ideal equiatomic composition. Studies on the Cu-41 at.% Pd alloy showed that the application of pressure raises the order-disorder transformation temperature at the rate of 1.4 C/kbar. [59Wat] investigated 13 to 28 at.% Pd alloys at temperatures above the order- disorder transformation point. They observed that in alloys with the two- dimensional APD structure, diffuse scattering corresponding to short-range order existed at 100 to 150 C above the transformation point. The resultant domain structure consisted of large pockets of completely disordered regions between ordered domains. Short-range order was observed by [67Kat] in a Cu-15 at.% Pd alloy deformed and annealed at various temperatures. 06Rue: R. Ruer, Z. Anorg. Chem., 51, 223-230 (1906) in German. 24Hol: S. Holgersson and E. Sedstrom, Ann. Phys. (Leipzig), 75, 143-162 (1924) in German. 32Lin: J.O. Linde, Ann. Phys., 15, 249-251 (1932) in German. 34Tay: R. Taylor, J. Inst. Met., 54, 255-272 (1934). 35Gra: L. Graf, Phys. Z, 36, 489-498 (1935) in German. 39Jon: F.W. Jones and C. Sykes, J. Inst. Met., 65, 419-433 (1939). 49Nem: V.A. Nemilov, A.A. Rudnitskii, and R.S. Polyakova, Izv. Sektora Platiny, 24, 26-34 (1949) in Russian. 54Gei: A.H. Geisler and J.B. Newkirk, Trans. AIME, 200, 1076-1082 (1954). 55Sch: K. Schubert, B. Kiefer, M. Wilkens, and R. Haufler, Z. Metallkd., 46, 692-715 (1955) in German. 56Wat: D. Watanabe and S. Ogawa, J. Phys. Soc. Jpn., 11(3), 226-239 (1956). 59Wat: D. Watanabe, J. Phys. Soc. Jpn., 14(4), 436-443 (1959). 67Kat: A.A. Katsnel›son, S.A. Alimov, and N.N. Stupina, Fiz. Met. Metalloved., 24(6), 1119-1120 (1967) in Russian; TR: Phys. Met. Metallogr., 24(6), 132-133 ( 1967). 71Sou: A. Soutter, A. Colson, and J. Hertz, M‚m. ђtud. Sci. Rev. Metall., 68(9) , 575-593 (1971) in French. 81Iwa: H. Iwasaki, Sci. Rep. Res. Inst. Tohoku Univ. A, 29, Suppl. (1), 135- 140 (1981). Submitted to the APD Program. Complete evaluation contains 7 figures, 9 tables, and 84 references. 1