Esqué-de Los Ojos Daniel, Pellicer Eva, Sort Jordi
Departament de Física, Universitat Autònoma de Barcelona, Bellaterra E-08193, Spain.
Manchester Materials Science Centre, The University of Manchester, Grosvenor Street, Manchester M1 7HS, UK.
Materials (Basel). 2016 May 11;9(5):355. doi: 10.3390/ma9050355.
In general, the influence of pore size is not considered when determining the Young's modulus of nanoporous materials. Here, we demonstrate that the pore size needs to be taken into account to properly assess the mechanical properties of these materials. Molecular dynamics simulations of spherical indentation experiments on single crystalline nanoporous Cu have been undertaken in systems with: (i) a constant degree of porosity and variable pore diameter; and (ii) a constant pore diameter and variable porosity degree. The classical Gibson and Ashby expression relating Young's modulus with the relative density of the nanoporous metal is modified to include the influence of the pore size. The simulations reveal that, for a fixed porosity degree, the mechanical behavior of materials with smaller pores differs more significantly from the behavior of the bulk, fully dense counterpart. This effect is ascribed to the increase of the overall surface area as the pore size is reduced, together with the reduced coordination number of the atoms located at the pores edges.
一般来说，在确定纳米多孔材料的杨氏模量时，孔径的影响通常不被考虑。在此，我们证明，为了正确评估这些材料的力学性能，需要考虑孔径。我们对单晶纳米多孔铜进行了球形压痕实验的分子动力学模拟，实验体系包括：(i)孔隙率恒定但孔径可变；(ii)孔径恒定但孔隙率可变。修正了将杨氏模量与纳米多孔金属的相对密度相关联的经典吉布森和阿什比表达式，以纳入孔径的影响。模拟结果表明，对于固定的孔隙率，孔径较小的材料的力学行为与整体致密对应物的行为差异更为显著。这种效应归因于随着孔径减小，总表面积增加，同时位于孔边缘的原子的配位数减少。
