(北京科技大学 新材料技术研究院，北京 100083)
摘 要: 采用定向凝固法制备藕状多孔镁，采用GLEEBLE-1500材料模拟实验机和直撞式霍普金森压杆(SHPB)实验设备，在10-3~1650 s-1的应变速率范围内，沿平行于气孔方向进行压缩变形实验，研究应变速率对藕状多孔镁压缩变形行为和力学性能的影响及影响机理。结果表明:藕状多孔镁沿平行于气孔方向的压缩变形过程主要包含线弹性变形阶段、局部坍塌变形阶段、低应力平台变形阶段和密实化阶段4个阶段，其中平台变形阶段较宽(应变在0.2~0.7之间)。平行于气孔方向压缩时，应变速率对藕状多孔镁的变形行为影响显著，在应变速率 ＜60 s-1条件下变形时，主要以孔壁首先发生局部剪切断裂，然后孔壁向孔隙内塌陷的方式变形，而在较高应变速率 =450~1650 s-1条件下变形时，主要以孔壁首先发生整体偏转，然后产生弯曲折断的方式变形;应变速率对藕状多孔镁的坍塌应力和平台应力有较明显的影响，其影响机制主要是由于不同应变速率时孔壁的变形方式发生变化，而受冲击波效应的影响不明显。
关键字: 藕状多孔镁;应变速率;变形行为;力学性能;变形机制
（Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:Lotus-type porous magnesium was fabricated by unidirectional solidification, and compressive experiments were subsequently conducted in the strain rate range of 10-3-1650 s-1 in the compressive direction parallel to the pores. A GLEEBLE-1500 materials simulation system and a split Hopkinson pressure bar (SHPB) were used to investigate the effect of strain rate on the compressive deformation behaviors and mechanical properties of lotus-type porous magnesium, and the influence mechanism of the strain rate was also analyzed. The results show that the compressive deformation process of lotus-type porous magnesium consists of a linear elastic stage, a collapse stage, a plateau stage and a densification stage at various strain rates, and the plateau stage has a quite wide range between 0.2-0.7 of the strain. The strain rates have significant effects on compressive deformation behaviors of lotus-type magnesium. When compressed at a lower strain rate less than 60 s-1, lotus-type magnesium deforms mainly in the way that pore wall firstly suffers a shear fracture in a local place of sample, and then, collapses into the hole. However, compressed at high strain rates between 450-1650 s-1, the main deformation way of lotus-type magnesium is that pore wall firstly deflects, and then buckles and broke during compressive deformation. The strain rates have obvious influence on the plateau stress and collapse stress, and the main mechanism is the deformation way of pore wall at a lower strain rate which is different from that at a high strain rate, but the shockwaves effect is not obvious.
Key words: lotus-type porous magnesium; strain rate; deformation behaviors; mechanical property; deformation mechanism
