Microstructure and mechanical properties of directionally solidified Al2O3/YAG binary eutectic ceramic prepared with induction heating zone melting

In order to reveal the dependence of the microstructure and mechanical properties of directionally solidified eutectic ceramic (DSEC) on the growth rate so as to further improve its performance, Al2O3/Y3Al5O12 (YAG) DSEC with diameter Phi 10.16 was prepared via induction heating zone melting (IHZM) method, and the effects of the growth rate on the phases' distribution, eutectic spacing, hardness and fracture toughness of the DSEC were investigated. XRD patterns show that the crystallinity of the eutectic ceramic significantly improved after directional solidification. The DSEC displays a typical irregular eutectic microstructure like mosaic, YAG phase formed the matrix in which Al2O3 phase embedded. The eutectic constant Is calculated lambda v(1)(/2) = 8.944, the microstructure evolution during solidification progress is shown via nucleating and growth mode. The hardness and fracture toughness of the DSEC are 1.89 times and 1.42 times those of the sintered ceramic, respectively. The relationship between the hardness, fracture toughness and the growth rate are expressed as H-v = 13.4 + 7.72v(1/)(4) and K-IC = 2.24 + 2.48v(1/4) via Hall-Petch equation.