Al2O3-ZrO2-Yb2O3 phase diagram. II. Liquidus surface

Abstract

The liquidus surface for the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram is constructed for the first time. No ternary compounds are found in the system. The liquidus surface is completed by seven primary crystallization fields. Two four-phase invariant eutectic equilibria, two four-phase invariant transition equilibria, and one three-phase invariant eutectic equilibrium are found in the ternary system. Since ZrO 2 interacts with other phases eutectically, composite materials can combine the uniqueThe liquidus surface of the ternary Al 2 O 3 -ZrO 2 -Yb 2 O 3 system has not been studied. Binary bounding systems have been sufficiently examined, their phase diagrams have been plotted [1-13]. The paper [15] represents experimental isothermal sections of the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram at 1250 and 1650°C and reveals conditionally quasibinary Yb 3 Al 5 O 12 (Yb 3 A 5 )-F section, where F is a solid solution of 28 mol.% Yb 2 O 3 in ZrO 2 . No new phases or noticeable regions of ternary solid solutions based on binary compounds or components have been revealed in the system. It is shown that eqiulibria in the system are determined by the ZrO 2 phase, which is most thermodynamically stable.The objective of this paper is to examine the liquidus surface of the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram and to plot its projection onto the concentration triangle. The initial substances, production of samples, and experimental procedure are detailed in [14]. Table 1 and Fig. 1 show the compositions of the alloys examined. The numeration corresponds to that in the table from [15]. In determining coordinates of the ternary eutectics, the composition of additional alloys was selected using the method of successive approximations. Based on the study, the projection of the Al 2 O 3 -ZrO 2 -Yb 2 O 3 liquidus surface has been projected onto the concentration triangle (Fig. 1). Liquidus temperatures, phase composition, and refractive indices for primary crystallized phases in alloys have been determined (Table 1). Table 2 summarizes the coordinates of invariant points of the ternary system, which were determined by examining the microstructures of alloys and by hightemperature differential thermal analysis (HDTA). To determine the type of invariant equilibria of the phases in the crystallization of ternary system alloys, the arrangement of phase compositions involved in the reactions and the direction in which temperature of the previous and subsequent monovariant three-phase crystallization processes

Phase diagrams of the systems Al2O3–ZrO2–Ln(Y)2O3 as a source of multiphase eutectics for creating composite structural and functional materials

“…3 -melting diagrams of the systems studied are presented. 5,[22][23][24][25][26][27][28][29] The main features of interaction in these systems are the lack of quasiternary compounds and appreciable regions of solid solutions based on quasibinary compounds and components. The most thermodynamically stable phases are oxides-components.…”

Directionally solidified eutectics in the Al2O3–ZrO2–Ln(Y)2O3 systems (Review)

“…As one of the results, the systematic examination of the phase diagrams of Al 2 O 3 -ZrO 2 -Ln 2 O 3 ternary systems (where Ln stands for lanthanides) established that Al 2 O 3 -rich eutectics formed in these systems, which had similar compositions but different phases [21,[95][96][97][98][99][100]. After the interaction features were established and complete phase diagrams of these systems were constructed over a wide range of temperatures and concentrations, estimate for all systems (where Ln = La-Lu) in the row was made, the coordinates of Al 2 O 3 -rich ternary eutectics were found (Table 1) and classified ( Table 2).…”

Al2O3-ZrO2-Yb2O3 phase diagram. IV. Vertical sections

“…Microstructure of cast alloys in the Al 2 O 3 -ZrO 2 -Yb 2 O 3 system at 15Z : a) alloy 15, black phase = AL, light phase = Yb 3 A 5 , fine gray phase in eutectic = F; b) alloy 16, light primary crystals of the Yb 3 A 5 phase, ternary eutectic AL + F + Yb 3 A 5 (E 2 ); c) alloy 17, large light primary crystals of the Yb 3 A 5 phase, ternary eutectic AL + F + Yb 3 A 5 (E 2 ); d) alloy 18, individual primary crystals of the Yb 3 A 5 phase, quasibinary eutectic Yb 3 A 5 + F (e 4 ); e) alloy 20, light primary crystals of the F phase, ternary eutectic Yb 3 A 5 + F + Yb 2 A (E 1 ); f) alloy 11, traces of the peritectic reaction C + L Yb 2 A + F with subsequent decomposition of the Yb 2 A phase into Yb 3 A 5 + C; magnification 1500 (a, d), 350 (b), 600 (c), 1350 (e), and 6750 (f) + Yb 3 A 5 )[2,3]. According to XRD, alloys 16 and 17 consist of three phases each: AL, F, and Yb 3 A 5 in different…”