含夹杂TiC-TiB2陶瓷强度的细观力学分析

Micromechanical Analysis of TiC-TiB2 Ceramic with Inclusion

摘要:

根据超重力合成TiC-TiB2装甲陶瓷的细观结构和断裂机理，建立TiC-TiB2装甲陶瓷细观强度模型，分两种失效形式讨论了氧化铝杂质颗粒对材料强度的影响。首先根据相互作用直推估计法计算了TiC-TiB2基体的等效刚度，认为氧化铝杂质颗粒稀疏分布在TiC-TiB2基体中，根据等效夹杂理论计算了杂质颗粒内部和附近残余应力和应力场分布，得出氧化铝杂质颗粒可能的失效形式；然后根据杂质颗粒可能出现的界面脱粘和颗粒破坏两种失效形式分别建立模型进行讨论，并以两者的最小值定义为复合材料的强度，分析了材料强度随细观结构和性能参数的变化规律，并与实验结果进行了对比。结果表明，模型能够反映材料失效机理，对于具有与本文相似细观结构的材料，杂质颗粒与等效基体的相对弹性性能和相对热膨胀性能、杂质颗粒尺寸、等效基体韧性等都可能影响杂质颗粒失效形式，但是杂质颗粒直径增加、基体韧性降低必然降低材料强度。对于含氧化铝杂质颗粒的TiC-TiB2装甲陶瓷，界面脱粘是杂质颗粒主要的失效形式。

Abstract:

A micromechanical was established based on the microstructure and the fracture mechanism of TiC-TiB2 ceramic prepared by combustion synthesis under high gravity. Two different failure modes were assumed in the micromechanical model to analysis the influence of alumina inclusions to ceramic strength. The equivalent stiffness of TiC-TiB2 matrix was calculated using the Interaction Direct Derivative (IDD) estimate. The alumina particles were considered sparse distribution in the TiC-TiB2 equivalent matrix, stress field contained residual stress in and around alumina particle was obtained by the equivalent inclusion method. According to the stress field around the particles, Al2O3 particles failure was considered as the origin of the composite fracture. Interface debonding and particle fracture were assumed as the two failure modes of particle failure, micro strength mechanical models based on these two modes were established and the minimum strength was defined as the composite strength. Composite strength variation with microstructure parameters and property parameters of different micro components was obtained, and the calculated strength was compared to the experimental data. The result shows that the strength model is reasonable in reflecting the composites failure mechanism; relative elastic and thermal properties between the particle and matrix, particle size and the equivalent matrix toughness can change the particle failure mode, and the particle size increasing and the equivalent matrix toughness decreasing result in composite strength necessarily. For TiC-TiB2 combustion synthesis composite with alumina inclusions, particle interface debonding is the primary fracture mechanism.