Al2O3-ZrO2-Yb2O3 phase diagram. III. Solidus surface and phase equilibria in alloy solidification

Abstract

The solidus surface for the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram is plotted onto the concentration triangle for the first time. It consists of four isothermal three-phase fields that correspond to two invariant eutectic equilibria and two invariant peritectic equilibria. The solidus surface also includes five ruled surfaces representing the end of crystallization in binary eutectics. The highest solidus temperature in the system is 2710°C, which is the melting temperature for pure ZrO 2 , while the lowest temperature is 1765°C, which is the melting temperature for the AL+F+Yb 3 A 5 ternary eutectic. No ternary compounds or noticeable areas of solid solutions based on components and binary compounds are found in the ternary system. The phase equilibrium diagram and reaction scheme for the equilibrium crystallization of Al 2 O 3 -ZrO 2 -Yb 2 O 3 alloys are plotted using data on bounding binary systems and liquidus and solidus surfaces.The objective of this paper is to plot the solidus surface of the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram onto the concentration triangle and examine the crystallization of alloys.Binary bounding systems have been adequately studied and their phase diagrams have been constructed [1][2][3][4][5][6][7][8][9][10][11][12][13]. The isothermal sections at 1250 and 1650°C and liquidus surface of the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram have been examined [14,15]. One conditionally quasibinary section Yb 3 Al 5 O 12 (Yb 3 A 5 )-(72% ZrO 2 · 28% Yb 2 O 3 )* that triangulates the ternary system has been found; its phase diagram has been constructed. No ternary compounds and noticeable areas of solid solutions have been found in the system. The interaction is mainly eutectic.The initial materials, production and examination of the samples are detailed in [16]. To determine the solidus temperatures and phase fields on the Al 2 O 3 -ZrO 2 -Yb 2 O 3 phase diagram, high-temperature differential thermal analysis (DTA), x-ray diffraction (XRD), and petrography were used. * The concentration is in mole%.

Mass spectrometric study of thermodynamic properties in the Yb2O3‐ZrO2 system at high temperatures

“…According to calculations, the compound Yb 4 Zr 3 O 12 (δ‐phase) is stable up to 1914 K, consistent with previous results . Serious disagreement between the experimental phase equilibrium data obtained by Wang and Lakiza et al . concerning the composition of the C‐phase in equilibrium with the δ‐phase and in equilibrium with fluorite in the Yb 2 O 3 ‐ZrO 2 system were pointed out by Fabrichnaya and Seifert .…”

“…and Stubican et al ., both indicating the lowest solubility of Yb 2 O 3 in fluorite, Wang indicating slightly higher Yb 2 O 3 solubility than other reports and Rouanet who indicated the highest solubility of Yb 2 O 3 in fluorite. Therefore, according to Wang, the stability range of the two‐phase region F + C in the Yb 2 O 3 ‐ZrO 2 system is much narrower than found by Lakiza et al . According to the calculations of Fabrichnaya and Seifert, the stability of the two‐phase region of F + C is as narrow as in work of Wang, but shifted more in the Yb 2 O 3 ‐rich composition of the system studied.…”

“…Wang indicated substantially higher solubility of ZrO 2 in the C‐phase than Lakiza et al . There are also discrepancies in the composition of the fluorite phase in equilibrium with the C‐phase between the data of Lakiza et al . and Stubican et al ., both indicating the lowest solubility of Yb 2 O 3 in fluorite, Wang indicating slightly higher Yb 2 O 3 solubility than other reports and Rouanet who indicated the highest solubility of Yb 2 O 3 in fluorite.…”

“…concerning the composition of the C‐phase in equilibrium with the δ‐phase and in equilibrium with fluorite in the Yb 2 O 3 ‐ZrO 2 system were pointed out by Fabrichnaya and Seifert . Wang indicated substantially higher solubility of ZrO 2 in the C‐phase than Lakiza et al . There are also discrepancies in the composition of the fluorite phase in equilibrium with the C‐phase between the data of Lakiza et al .…”

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.…”