Microstructure and mechanical properties of Al2O3/YAG eutectic ceramic grown by horizontal directional solidification method

摘要

Al2O3/Y3Al5O12(YAG) eutectic ceramic with the dimension of 180 mm x 140 mm x 30 mm was firstly grown in vacuum by Horizontal Directional Solidification (HDS) method. Half of the sample was annealed for 100 h at 1973 K in the air. The oxygen vacancies were found to be fully compensated by annealing in X-ray photoelectron spectroscopy. The HDS-Al2O3/YAG eutectic showed no grain growth after longtime annealing treatment and the two constituent phases were three-dimensionally interpenetrated without grain boundaries. The average eutectic interspacing is 3.1 +/- 1.8 mu m. The density rho, hardness H-v, fracture toughness K-IC, compression stress sigma(c) (to 8% strain) and flexural stress sigma(f) of the as-grown and annealed samples were measured at room temperature, the values changing from 4.26 g/cm(3) to 4.39 g/cm(3), 16.04 +/- 0.75 GPa to 16.79 +/- 0.45 GPa, 2.69 +/- 0.06 MPa m(1/2) to 3.07 +/- 0.05 MPa m(1/2), 1188 MPa-1278 MPa and 320-340 MPa to 345-370 MPa, respectively. The crack arrest, deflection and branching enhanced the resistance of crack propagation after Vickers experiments. The flexural fracture surface of the as-grown samples shows mainly transgranular fracture, while mixed fracture of intergranular and transgranular is observed for the annealed samples. (C) 2015 Elsevier B.V. All rights reserved.