We use Molecular Dynamics simulations to study mechanical behaviors of crystalline silicon nitride nanoporous membranes with different pore distribution upon tensile loading along the armchair direction. Our results suggest that the proper introduction of the pores in nanoporous membranes leads to the transition from brittle failure into ductile failure mechanism. This transition is accompanied with the change of plastic deformation mechanism from either localization of Von-Mises strain within isolated regions or a network of zigzag shear bands into the formation of a network of straight shear bands. We also found that the formation of zigzag shear bands upon plastic deformation leads to strain hardening and thus increases the strength. Our results suggest new strategies for improving strength and ductility of nanoporous membranes.

我们使用分子动力学模拟来研究具有不同孔隙分布的结晶氮化硅纳米多孔膜在沿扶手椅方向的拉伸载荷下的力学行为。我们的结果表明，在纳米多孔膜中适当引入孔会导致从脆性破坏向延性破坏机制的转变。这种转变伴随着塑性变形机制的变化，从孤立区域内的Von-Mises应变局部化或锯齿形剪切带网络转变为直形剪切带网络。我们还发现，塑性变形后形成锯齿形剪切带会导致应变硬化，从而提高强度。我们的结果提出了提高纳米多孔膜强度和延展性的新策略。