HIGH TEMPERATURE CREEP BEHAVIOUR OF SINGLE CRYSTAL OXIDES

摘要

The creep resistance of several single crystal oxides is evaluated on the basis of creep data from different sources using a Larson-Miller (L-M) method. The possible creep mechanisms involved in high temperature creep deformation of single crystal oxides are discussed by comparing the collected creep data with theoretical creep models. The high temperature creep of single crystal oxides is generally considered as a diffusion-controlled process: dislocation climb controlled by the lattice diffusion of the slowest moving species (power law) at moderately high stresses, Harper-Dorn creep at low stresses, and power law breakdown at high stresses. The relative comparison of the creep data from different sources using the L-M method and the general analysis about the high temperature creep behaviour indicate that single crystal oxides with a precise stoichiometric composition, complex crystal structure and selected orientation such as [111] oriented YAG (Y3Al5O12), c-axis Al2O3, [110] oriented MgAl2O4 are potential candidates as reinforcements for very high temperature structural applications. [References: 44]