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

Abstract

The current status of research on high-temperature composite oxide ceramics in the Al 2 O 3 -ZrO 2 -Ln 2 O 3 systems (Ln are lanthanides, Y) is reviewed. It is emphasized that their use as structural materials at high temperatures (up to 1650°C) is promising. Conditions for growing binary and ternary eutectic composites and their properties are described. Weak and strong aspects of these materials are pointed out. The role of phase diagrams in developing high-temperature in situ composites is shown.

Nanocrystalline Alumina-Zirconia-Based Eutectic Ceramics Fabricated with High-Energy Beams: Principle, Solidification Techniques, Microstructure and Mechanical Properties

“…Other important aspects are size, shape and crystallographic orientation, as well as the morphologies and nature of the interfaces between eutectic phases, colonies and grains. The microstructures and crystallography of directionally solidified oxide eutectic ceramics were reported by LLorca et al [96], Merino et al [97] and Lakiza [98]. Those previous results were taken into consideration here, but this discussion is mainly focused on alumina-zirconia-based nanoeutectic ceramics with regard to the abovementioned aspects.…”

“…In particular, hardness, fracture toughness, wear, thermal stability, strength and creep, as well as thermal emission and optical transparency properties, have been studied. The main mechanical properties and emerging functional applications of DSE ceramics were reviewed by Hirano [107], LLorca et al [96], Lakiza [98], Zhang et al [108] and Orera [101]. Herein, we will only focus on the major recent developments of the mechanical aspects of alumina-based nanoeutectic ceramics.…”

Directionally Solidified Al2O3/Er3Al5O12 and Al2O3/Yb3Al5O12 Eutectic Ceramics Prepared by Optical Floating Zone Melting

“…Co., Ltd., Huizhou, China) and Al2O3 (Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) were used to fabricate the Al2O3/ErAG and Al2O3/YbAG eutectic composites. The powders were mixed according to the binary eutectic compositions with mole ratio of Al2O3:Er2O3=81:19 [20] and Al2O3:Yb2O3=81.5:19.5 [21] , respectively. The starting powders were ball milled 24 h in a Si3N4 jar, with Si3N4 balls and ethanol as media.…”

The Al2O3–HfO2–La2O3 phase diagram. I. Liquidus and solidus surfaces

“…In this system, compound La 2 Hf 2 O 7 (LH 2 ) is formed with pyrochlore-type structure; it melts congruently at 2420°C and has quite a wide homogeneity range that varies with temperature. The LH 2 phase forms a eutectic with starting oxides at 2330°C and 23% La 2 O 3 and at 2070°C and 64% La 2 H + LH 2 . The solubility in the X-La 2 O 3 -based phase is 13% HfO 2 at 1960°C in eutectoid transformation X H + LH 2 and to 17% HfO 2 at 2085°C in eutectoid transformation L X + LH 2 .…”