玻璃空心微球/铝基多孔复合材料的制备及其准静态压缩特性和吸能性能

Preparation of glass microspheres/aluminum matrix syntactic foam and its quasi-static compressive characteristic and energy absorption

铝基多孔复合材料由铝基体和空心微球复合而成,兼具轻质与吸能特性。本文采用放电等离子烧结(SPS)方法制备玻璃空心微球/铝基多孔复合材料,通过光学显微镜、SEM、准静态压缩原位观察和数字图像相关技术表征,分析了空心微球含量及尺寸对复合材料准静态压缩变形行为和吸能性能的影响。结果表明:两步升温SPS烧结制备所得的铝基多孔复合材料,其微球弥散均匀嵌于铝基体中,铝基体熔合致密。随空心微球含量增加,复合材料压缩应力整体降低,屈服平台区扩大但由平滑转变为锯齿状,压缩变形行为从较均匀的鼓状形变逐渐发展为脆性剪切,微球体积分数为50vol%的多孔复合材料吸能能力为23.6 J·cm^(−3),高于体积分数为30vol%和70vol%的多孔复合材料,复合材料吸能能力与微球含量间存在最优对应关系。小尺寸微球具有更好的抗压能力,随小尺寸微球占比的提高,复合材料微观上可承受更高的应力-应变集中,宏观上剪切形变的压缩应变增大,本文中小尺寸微球多孔复合材料的峰值应力和吸能能力分别为89.4 MPa和29.0 J·cm^(−3),与大尺寸微球多孔复合材料相比分别提高23.5%和22.9%。

Aluminum matrix syntactic foams are a novel class of cellular materials synthesized by hollow particles and aluminum matrix,which exhibit lightweight and high energy-absorbing capacity.In this study,the glass microspheres/aluminum matrix syntactic foams were prepared by the spark plasma sintering(SPS)method.The effects of the content and size of microspheres on the quasi-static compressive deformation behavior and energy absorption properties of the syntactic foams were analyzed by optical microscope(OM),SEM,quasi-static compression in situ observation,and digital image correlation(DIC)characterization.The results show that the microspheres of aluminum matrix syntactic foams prepared by two-step heating SPS sintering are uniformly embedded in the aluminum matrix,while the aluminum matrix is completely fused with high densification.With the increase of the microsphere content,the compressive stress of the syntactic foam decreases as a whole,meanwhile,the yield plateau expands and changes from smooth to zigzag.In addition,the compressive deformation behavior gradually develops from a relatively uniform drum-shaped deformation to brittle shear.The energy absorption capacity of the syntactic foam with the volume fraction of 50vol%is 23.6 J·cm^(−3),which is higher than that with the volume fraction of 30vol%and 70vol%.There is an optimal correspondence between the energy absorption capacity and the microsphere content of the syntactic foam.Small-sized microspheres have better compressive resistance.With the increase of the small-sized microsphere proportion,the syntactic foams can withstand higher stress and strain concentration on the microscopic level,as a result,the compressive strain of shear deformation increases on the macro level.In this study,the peak stress and energy absorption capacity of the syntactic foam with small-sized microspheres are 89.4 MPa and 29.0 J·cm^(−3),which are 23.5%and 22.9%higher than those of the syntactic foam with largesized microsphere,respectively.