The Dy-Zn phase diagram

Abstract

The dysprosium-zinc phase diagram has been investigated over its entire composition range by using differential thermal analysis, (DTA) metallographic analysis, X-ray powder diffraction, and electron probe microanalysis (EPMA). Seven intermetallic phases have been found and their structures confirmed. DyZn, DyZn 2 , Dy 13 Zn 58 , and Dy 2 Zn 17 melt congruently at 1095 °C, 1050 °C, 930 °C, and 930 °C, respectively. DyZn 3 , Dy 3 Zn 11 , and DyZn 12 form through peritectic reactions at 895 °C, about 900 °C and 685 °C, respectively. Four eutectic reactions occur at 850 °C and 30.0 at pct Zn (between (Dy) and DyZn), 990 °C and 60.0 at pct Zn (between DyZn and DyZn 2 ), 885 °C and 76.0 at pct Zn (between DyZn 3 and Dy 3 Zn 11 ), and 875 °C and 85.0 at pct Zn (involving Dy 13 Zn 58 and Dy 2 Zn 17 ). The Dy-rich end presents a catatectic equilibrium; a degenerate invariant effect has been found in the Zn-rich region. The phase equilibria of the Dy-Zn alloys are discussed and compared with those of the other known RE-Zn systems (RE = rare earth metal) in view of the regular change in the relative stabilities of the phases across the lanthanide series A. SACCONE and S. DELFINO, Full Professors, A.M. CARDINALE, Researcher, and R. FERRO, Professor Emeritus, are with the

The Crystal Structure of GdZn3

“…They can be described as distorted trigonal prisms with three additional atoms on lateral faces and one atom on an edge. Similar coordination polyhedra of Zn atoms are found in the neighboring GdZn 2 [4] and Gd 3 Zn 11 [1,2] phases. Strongly distorted [Zn3Zn 7 Gd 5 ] cuboctahedra are centered by Zn3.…”

“…2). This polyhedron has no analogs within Gd x Zn y structures, though the coordination number is between minimal 14 in the Gd-rich phase GdZn [3] and maximal 20 in the Zn-richer phases Gd 3 Zn 11 [1,2], Gd 3 Zn 22 [1,2] and GdZn 12 [1,2,10]. Two types of polyhedra are observed for the Zn atoms.…”

“…The binary system Gd-Zn is rich in intermetallic phases, especially in the region with high content of Zn [1,2]. Ten binary compounds (with the structure types (ST) in parentheses) with the compositions: GdZn (ST CsCl) [3], GdZn 2 [1,2,10] have been reported.…”

“…Ten binary compounds (with the structure types (ST) in parentheses) with the compositions: GdZn (ST CsCl) [3], GdZn 2 [1,2,10] have been reported. They have mostly been characterized thermodynamically as part of temperaturecomposition diagram constructions [2]. However, the majority of the phases are not well investigated and characterized crystallographically.…”

“…The structure modification can be achieved either by temperature treatment, a slight shift in composition or small admixtures of a third component. The existence of a binary compound GdZn 3 was reported, and it was stated that it adopts the YZn 3 structure type [1,2,5], however, only cell constants have been refined by means of powder X-ray diffraction, and no structure determination was performed. Moreover, it was found that CeZn 3 has a slightly different structure with space group Cmcm [1].…”