Abstract
This work was inspired by previous experiments which managed to establish an optimal template-dealloying route to prepare ultralow density metal foams. In this study, we propose a new analytical–numerical model of hollow-structured metal foams with structural hierarchy to predict its stiffness and strength. The two-level model comprises a main backbone and a secondary nanoporous structure. The main backbone is composed of hollow sphere-packing architecture, while the secondary one is constructed of a bicontinuous nanoporous network proposed to describe the nanoscale interactions in the shell. Firstly, two nanoporous models with different geometries are generated by Voronoi tessellation, then the scaling laws of the mechanical properties are determined as a function of relative density by finite volume simulation. Furthermore, the scaling laws are applied to identify the uniaxial compression behavior of metal foams. It is shown that the thickness and relative density highly influence the Young’s modulus and yield strength, and vacancy defect determines the foams being self-supported. The present study provides not only new insights into the mechanical behaviors of both nanoporous metals and metal foams, but also a practical guide for their fabrication and application.
Highlights
Low-density metal foams have been of great interest in the past decade since the subtle combination of the property features of metals and porous structure [1,2,3]
The relative density ρ significantly influences the deformation behavior of np-Au in stiffness, seen in the initial slope of the curves, as well as in strength, visible as the 0.2% offset stress indicated on the curves by filled circles
The firstly compression between np-Au I and np-Au II shows that the former has a slightly higher stiffness and strength than the latter, the results indicate that the pore size and ligament diameter subjected to Gaussian distributions tend to damage the mechanical properties of nanoporous metals
Summary
Low-density metal foams have been of great interest in the past decade since the subtle combination of the property features of metals and porous structure [1,2,3]. Metal foams with structural hierarchy present promising application prospects in various fields, such as supercapacitor [4], catalytic [5], sensors [6,7], controlled drug release [8] and tissue scaffold [9], benefitting from the merits of high porosity, high surface area, ultralow density, high conductivity, biocompatibility, and outstanding mechanical Performance [10]. Synthetic hierarchically porous materials constructed by natural systems could be used to introduce advantageous features in terms of performance and sustainability. The main advantageous features of hierarchically porous materials are numerous synthesis approaches, tunable porous structures, controllable macroscopic morphologies, adjustable multiple functions, and potential wide utilization [11,12].
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