Solid-state reaction, microstructure and phase relations in the ZrO2-rich region of the ZrO2-Yb2O3 system

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

“…The solidus also includes ruled final crystallization surfaces for five monovariant eutectics: AL + T, AL + F, Yb 3 A 5 + F, Yb 2 A + F, and Yb 2 A + C. The ruled final crystallization surface of the monovariant eutectic AL + T is adjacent to the binary bounding Al 2 O 3 -ZrO 2 system and is completed by the conoids that rest on the composition of the stoichiometric AL phase and T phase, which is a solid solution of Yb 2 O 3 in ZrO 2 . The composition of the T solid solution varies between 0 and 2% Yb 2 O 3 [10,13]. This ruled surface smoothly goes down from 1860ºC of the two-phase eutectic AL + ZrO 2 (e 6 ) to 1775ºC of the conoid triangle AL-F-T.…”

“…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].…”

“…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].…”

“…The T phase is a solid solution based on tetragonal ZrO 2 modification containing 2% Yb 2 O 3 at the temperature of conoid triangle [10,13]. The F phase is a solid solution based on cubic ZrO 2 modification containing 4% Yb 2 O 3 whose composition was determined using its mean lattice parameter a F = 0.5121 nm in alloy 34 and data from [10,13]. The coordinates of the conoid triangle AL-F-T are also confirmed by XRD, according to which alloy 1 contains the F, T, and AL phases (Table 1).…”

The Al2O3-ZrO2-Yb2O3 phase diagram. I. Isothermal sections at 1250 and 1650°C

“…Four nonvariant points have been found on the Al 2 O 3 -Yb 2 O 3 liquidus surface: two eutectic (Al 2 O 3 + Yb 3 A 5 , 1750°C, 20% Yb 2 O 3 and Yb 3 A 5 + Yb 2 A, 1850ºC, 51% Yb 2 O 3 ), one peritectic (1925°C, 60% Yb 2 O 3 ), and one metatectic (2380ºC, 98% Yb 2 O 3 ), which represents the Yb 2 O 3 (C H) phase transformation occurring over a narrow temperature range at about 2380°C [7]. ZrO 2 -Yb 2 O 3 is a eutectic system with a peak at 2820°C, 25% Yb 2 O 3 , and eutectic point at 2400°C, 85% Yb 2 O 3 [8][9][10][11][12][13][14]. A peritectic point at 2460°C, 21% ZrO 2 has been found on the liquidus, its liquid participates in L + F C. There are significant regions of solid solutions based on components in the system.…”