SHS制备纳米/微米Al2O3-ZrO2复相陶瓷力学行为研究

Al2O3-ZrO2复相陶瓷相对密度与硬度均随ZrO2体积分数增加而下降,复相陶瓷的硬度和晶粒尺寸的关系符合正Hall-Patch关系.vickers压痕试验发现,该复相陶瓷的压痕裂纹系统属于中位裂纹系统,而引发复相陶瓷中位裂纹扩展的压痕压制载荷临界值为30kg;Vickers压痕SEM形貌观察显示,亚共晶成分复相陶瓷具有较大的断裂韧性和较高的塑性形变行为.裂纹扩展路径的SEM观察,该复相陶瓷中的裂纹扩展主要受晶内型结构共晶组织中ZrO2纳米相所控制;XRD物相定量分析表明在该复相陶瓷的增韧行为中,ZrO2相所具有的传统的应力诱发相变增韧机制和微裂纹增韧机制较微弱,而纳米相增韧机制则发挥着决定性作用,使得该复相陶瓷中的晶界和相界对陶瓷断裂行为有着极大的影响.

Investigation on Mechanical Behaviors of Nano-micron Al2O3-ZrO2 Composite Ceramics Fabricated by SHS

The relative density and hardness of the composite ceramics are reduced with increasing the volume fraction of ZrO_2 in composite ceramics, and the relation of hardness and grain size of the composite ceramics is coincident with positive Hall-Patch relation. Vickers indentation test indicates that indentation crack system of the composite ceramics belongs to the median crack system, critical value of indentation load which induces the median crack to extend is 30kg. SEM observation on morphologies of Vickers indentations indicates that composite ceramics with hypoeutectic composition is performed with high fracturetoughness and high plasticity. SEM observation on crack paths shows that crack extension in the composite ceramics is mainly controlled by ZrO_2 nano-phase inthe eutecticums with intragranular structure. XRD quantitative analyses indicate that traditional stress induced ZrO_2 transformation toughening mechanism and micro-crack toughening mechanism in the composite ceramics were executed very weakly, and nano-phase toughening mechanism is brought into playing determinative influences on toughening behaviors of composite ceramics, causing eutecticum boundary and phase interface to have a great influence on fracture behaviors of the composite ceramics.