In-situ synthesis of alumina-matrix oxide/oxide composites and performance enhancement by multiple toughening

采用反应烧结法原位合成了六铝酸钡和氧化锆增强氧化铝基复合材料。原位合成的复合材料表现出细长的六铝酸钡和等轴氧化锆颗粒的显微结构特征。Ba-β-Al_2 O_3相的形成可能是由于Ba阳离子沿着基面的优先扩散。TZP或Y2 O3的掺入促进了复合材料的致密化和由于氧化钇向单斜氧化锆的扩散而形成的四相氧化锆，所述单斜氧化锆是在烧结期间通过氧化铝和锆酸钡之间的反应产生的。所合成的氧化铝基复合材料显示出高的断裂韧性，作为多个增韧效应，包括裂纹偏转，裂纹桥接，和马氏体相变的氧化锆从四方相到单斜相的结果。

Alumina matrix composites reinforced with barium hexaluminate and zirconia were synthesized in situ through reactive sintering of alumina and barium zirconate powder mixtures. The in-situ synthesized composites exhibited a microstructural feature of the elongated barium hexaluminate and equiaxed zirconia particles. The formation of Ba-beta-Al2O3 phase with an elongated morphology is likely to be attributed to preferred diffusion of Ba cations along the basal planes. The incorporation of TZP or Y2O3 promotes densification of the composites and formation of tetragonal zirconia due to diffusion of yttria to monoclinic zirconia, which is generated through reaction between alumina and barium zirconate during sintering. The synthesized alumina matrix composites showed high fracture toughness, as a result of multiple toughening effects including crack deflection, crack bridging, and martensitic transformation of zirconia from tetragonal to monoclinic phases.