(北京科技大學(xué) 新材料技術(shù)研究院，北京 100083)
摘 要: 采用定向凝固法制備藕狀多孔鎂，采用GLEEBLE-1500材料模擬實(shí)驗(yàn)機(jī)和直撞式霍普金森壓桿(SHPB)實(shí)驗(yàn)設(shè)備，在10-3~1650 s-1的應(yīng)變速率范圍內(nèi)，沿平行于氣孔方向進(jìn)行壓縮變形實(shí)驗(yàn)，研究應(yīng)變速率對藕狀多孔鎂壓縮變形行為和力學(xué)性能的影響及影響機(jī)理。結(jié)果表明:藕狀多孔鎂沿平行于氣孔方向的壓縮變形過程主要包含線彈性變形階段、局部坍塌變形階段、低應(yīng)力平臺變形階段和密實(shí)化階段4個階段，其中平臺變形階段較寬(應(yīng)變在0.2~0.7之間)。平行于氣孔方向壓縮時，應(yīng)變速率對藕狀多孔鎂的變形行為影響顯著，在應(yīng)變速率 ＜60 s-1條件下變形時，主要以孔壁首先發(fā)生局部剪切斷裂，然后孔壁向孔隙內(nèi)塌陷的方式變形，而在較高應(yīng)變速率 =450~1650 s-1條件下變形時，主要以孔壁首先發(fā)生整體偏轉(zhuǎn)，然后產(chǎn)生彎曲折斷的方式變形;應(yīng)變速率對藕狀多孔鎂的坍塌應(yīng)力和平臺應(yīng)力有較明顯的影響，其影響機(jī)制主要是由于不同應(yīng)變速率時孔壁的變形方式發(fā)生變化，而受沖擊波效應(yīng)的影響不明顯。
關(guān)鍵字: 藕狀多孔鎂;應(yīng)變速率;變形行為;力學(xué)性能;變形機(jī)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
