Effect of porosity on the elastic response of brittle materials: An embedded-atom method approach

摘要

The values for Young's modulus of porous single-crystal Ni in the [100] and [111] directions are computed using the embedded-atom method (EAM). Both pore volume fraction and pore size (defined by ratio S/R of the flaw size to pore radius) are varied. A reduction in Young's modulus with increasing pore volume fraction and with increasing S/R ratio is observed in the EAM simulations, in good agreement with a recent theoretical model proposed by Krstic and Erickson. A porous Sigma = 5, [100] grain boundary also demonstrates a marked reduction in Young's modulus compared with the pore-free Sigma = 5, [100] grain boundary. These results suggest that recent literature values demonstrating greatly reduced Young's modulus for some nanocrystalline materials (compared with conventional polycrystalline materials) may be a consequence of residual porosity in the material. Poisson's ratio is calculated for aligned pores with stress applied in the [100] direction. The crack-opening displacement is qualitatively and quantitatively confirmed for pores containing annular flaws.