氧化铝陶瓷受冲击压缩破坏的细观机理研究

Investigation on Mesoscale Failure Mechanism of Alumina under Shock Compression

利用激光速度干涉仪VISAR测试了平板冲击压缩下不同厚度氧化铝陶瓷样品的自由面速度历程。根据自由面速度历程上表征"破坏波"现象的二次压缩信号计算获得了破坏波的传播轨迹,指出陶瓷中破坏波的形成传播机制主要由细观力学行为控制。进一步基于氧化铝陶瓷的细观扫描图像,构建了含晶相、玻璃相等细观特征的力学模型。数值模拟了冲击压缩下陶瓷材料的细观破坏过程,从细观层次分析了破坏波的形成传播机理。结果表明,陶瓷中破坏阵面的形成主要依赖于原生微缺陷在冲击载荷下的快速形核扩展过程,其传播特性满足扩散过程。

With the aid of the VISAR,the velocity histories of rear free surface of the alumina with different thicknesses under plate impact loading were recorded.The failure wave trajectory was obtained from the recompression signals observed in the temporal curves of rear free surface velocity of samples.The results indicate that the generation and propagation mechanisms of failure wave are closely related to the mesoscale failure properties of alumina.The mesostructure properties of tested alumina were studied according to the SEM of alumina samples.Based on these properties,a mesoscopic model of alumina,including alumina grain phase and glassy phase,is established.Further,mesoscale simulations were presented to analyze the mesoscale failure properties of alumina.And the generation and propagation mechanisms of failure waves in shocked alumina were researched at the mesoscale.The results show that the nucleation and growth of rapid in-situ grain boundary microcracks under impact loading give rise to the failure wave phenomenon,and the failure wave propagation may be governed by diffusion processes.