颗粒增强金属基复合材料SiCp/2024Al动态压缩力学性能实验研究

EXPERIMENTAL STUDY ON DYNAMIC COMPRESSION PROPERTIES OF SiCp/2024Al PARTICLES-REINFOCED METAL MATRIX COMPOSITES

  • 摘要: 利用分离式霍普金森压杆(SHPB)对颗粒体积分数为50%的颗粒增强金属基复合材料SiCp/2024Al进行了动态压缩试验,并得到了应变率范围为1250/s―2500/s的动态应力-应变曲线,且与准静态压缩下的结果进行了对比。实验中根据SHPB理论假设,采用波形整形技术,使得试件在加载过程中处于应力平衡和均匀变形状态。试验结果表明:随着应变率的增大,与准静态结果相比,在高应变率下复合材料的流动应力和塑性应变有明显的增大,具有显著的应变率敏感率,且破坏形式表现出脆性特征。试件断口扫描电镜实验结果发现基体由于绝热压缩生成的热而发生了明显的熔化现象。该文还讨论了应变率和颗粒体积分数对复合材料破坏模式和变形机理的 影响。

     

    Abstract: The dynamic compression tests of SiCp/2024Al metal matrix composites with the 50% fraction of particles were performed by Split Hopkinson Pressure Bar(SHPB. Dynamic stress-strain curves at the strain rates ranging from 1250/s to 2500/s were obtained, compared to the quasi-static results. Based on the SHPB hypothesis, pulse shaping technique was employed to maintain the specimen in the equilibrium and uniform deformation state over the testing course. The results showed that the flow stress and plastic strain of the composite considerably increased at high strain rates compared with the quasi-static results. The composites showed obvious strain-rate sensitivity. And the failure modes were brittle fracture. The fracturing surfaces were characterized by a scanning electron microscopy. It was obvious that the matrix was softened/melted by heat generated during adiabatic compression. The effects of strain rates and particle fraction on the failure mode and deformation mechanism were also discussed.

     

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