Creep Behavior of In-Situ Single-Crystal Oxide Eutectic Composites

Abstract

Compressive creep tests were conducted for in-situ single-crystal alumina/yttrium aluminum garnet (Al₂O₃/Y₃Al₅O₁₂(YAG)) and alumina/gadolinium aluminum provskite (Al₂O₃/GdAlO₃(GAP)) eutectic composites at temperatures between 1723-1923 K under stress ranges of 100-450 MPa in air environments. These oxide eutectic composites exhibited a stress exponent of 5-10, indicative of compressive creep behavior characterized by a dislocation mechanism. Activation energies for creep deformation were 800-1000 kJ/mol, in agreement with that of self-diffusion for c-axis Al₂O₃ single-crystal. The Al₂O₃/YAG exhibited a slightly decrease in creep rate by about twice for the Al₂O₃/GAP. The Larson-Miller method provided effective means of comparing the creep resistance of oxides on the basis of results obtained under different stresses and temperatures.