High‐Temperature Tensile Strength of Er₂O₃‐Doped ZrO₂ Single Crystals

Abstract

The deformation and fracture mechanisms in tension were studied in single‐crystal Er2O3‐doped ZrO2 monofilaments processed by the laser‐heated floating zone method. Tensile tests were carried out between 25° and 1400°C at different loading rates and the dominant deformation and fracture mechanisms were determined from the shape of the stress–strain curves, the morphology of the fracture surfaces, and the evidence provided by monofilaments deformed at high temperature and broken at ambient temperature. The tensile strength presented a minimum at 600°–800°C and it was controlled by the slow growth of a crack from the surface. This mechanism was also dominant in some monofilaments tested at 1000°C and above, while others showed extensive plastic deformation before fracture at these temperatures. The strength of plastically deformed monofilaments was significantly higher than those which failed by slow crack growth due to the marked strain hardening capacity of this material.

Directionally Solidified Eutectic Ceramics for Multifunctional Aerospace Applications

“…The strong interphase bonding and large aspect ratio of the constituent phases characteristic of the directionally solidified eutectic ceramics are in large part responsible for their superior creep resistance and high temperature microstructural stability [1]. The interfaces between the two phases of eutectic structure typically adopt low-energy orientation relationships during the directional solidification process, this provides strong bonding [ 5,6,7] and prevents significant interface debonding. The degree of microstructural anisotropy of DSE ceramics, although a necessary condition in promoting improvements in high temperature mechanical properties, is insufficient to achieve higher toughness.…”

Degradación ambiental de las propiedades mecánicas de fibras monocristalinas de circona dopada con erbia

“…2, 3 y 4, podemos estimar la cinética de crecimiento de la grieta en un monocristal de circona tetragonal suponiendo que la velocidad de la grieta, ν, sigue una ley del tipo ν=AK n , donde K es el factor de intensidad de tensiones en la punta de la grieta, y A y n son dos constantes de dependen del material y de las condiciones ambientales. Las tensiones de rotura estarán relacionadas con las velocidades de deformación según [24][25][26][27][28] (1) donde E es el módulo elástico, e • es la velocidad de deformación, σ 0 la resistencia inerte, K c la tenacidad e Y una constante geométrica. A partir de la pendiente de la gráfica logσ-log e…”