Synthesis,Mechanical And Electrochemical Properties Of Novel Nanoporous Copper Composites

This work studies the microstructure,mechanical properties and fracture deformation mechanism of the NPC/BMG composite rods(NPC/BMG: nanoporous copper/bulk metallic glass)fabricated by facilely modulating the dealloying time in HF.It is observed that the thicker NPC tubular layer can absorb more excess free energy within the shear band due to the enhanced interactions between the NPC layer and the inner BMG matrix,which delay the occurrence and development of a shear crack.Meanwhile,the NPC layer also can act as a plastic shielding for reducing the stress concentration at the shear crack tip of BMG matrix by absorbing its high local energy.This work mainly focused on preparing the bulk glassy rods with a diameter up to 2 mm by copper-mold casting.Subsequently,the dealloying was performed in 0.05 M HF acid aqueous solution with the duration ranging from 1 to 5 days,and the as-dealloyed samples is labeled as NPC/BMG rod-1,2 and 3,respectively.The microstructure,morphology,mechanical and electrochemical properties of the NPC/BMG were examined by XRD,SEM,an Instron mechanical testing machine and electrochemical workstation,respectively.Experimental results:(1)The NPC/BMG composite rods show the unique architecture of inner rod-shaped Cu-Zr-Al amorphous phase core and outer tube-shaped NPC layer;(2)The NPC/BMG rod demonstrates a hierarchical architecture with ligament width and nanopore size gradient through the whole NPC tubular depth;(3)The composite rods demonstrate the excellent combination of high strength of 0.9 GPa ~ 1.5 GPa and large compressive strain of 2.9% ~ 5.5%;(4)Differing from a monolithic BMG,the composite rods displays four distinct deformation characteristics on the fracture surface;(5)The appearance of many dimple-like patterns on the transition zone and the glassy matrix adjacent to the transition zone gives clear evidence that the outer NPC with nanoporous structure interacts with the inner glassy matrix.Moreover,the thicker NPC layer results in the formation of the wider buffer deformation zone,which is responsible for a significant improvement in the compressive strain;(6)The composites exhibit good electrochemical characteristics to the glucose solution;(7)The rods show low impedance values.