Microstructure Evolution and Model Analysis of Al2O3/ZrO2 Hypoeutectic Ceramic During Rapid Solidification

摘要

Rapid solidification of the super high-temperature Al2O3/ZrO2 melt was studied by a novel method. The melt was prepared by explosion reaction using Al and Zr(NO3)4 as raw materials and then sprayed to Cu-plate. The heat transfer during the solidification process was analyzed by one-dimensional Finite Element Analysis. The cooling rate of the melt decreased with the increasing distance from the Cu-plate. According to the microstructure evolution, the coating can be divided into four areas: amorphous, nano-crystalline, cellular and dendrite crystal layer. The amorphous and nano-crystalline (50~100 nm) layers can be obtained at the cooling rate of about 1.68~7.76 × 105K/s and 0.48~1.68 × 105K/s, respectively, while the cooling rate of the cellular and dendrite crystal layers were about 0.26~0.48 × 105K/s and 0.14~0.26 × 105K/s, respectively. The microstructure of the hypoeutectic ceramics shows that the nano-crystalline, cellular and dendritic crystals of the Al2O3 phases were embedded in the Al2O3/ZrO2 eutectic matrix.