中文摘要：

在含孔隙微纳晶材料受单轴压缩载荷下的大塑性变形中,由于孔洞与基体变形的不匹配,在孔洞周围将产生大量的几何必需位错,论文假设这些位错均匀地从孔洞表面向其内部发射,促使孔洞周围先产生局部非均匀变形,从而导致微纳晶镍试样内孔隙率的变化.基于这种假设论文首先建立了单轴压缩载荷下孔洞的演化发展模型,并用此模型预测了孔隙率的变化,将其与实验测定值进行了比较,结果表明孔洞演化发展模型具有一定合理性.在此基础上,讨论了固定孔隙率和演化发展的孔隙率对不同晶粒尺寸和不同应变速率下的微纳晶镍试样力学行为的影响.

英文摘要：

To study the effect of pores on the mechanical properties of porous bulk micro/nanocrystalline Ni sample further,a model of pore evolution under uniaxial compression test was firstly established on the basis of the emission of geometrically necessary dislocations due to the mismatch between the pore and matrix.At the same time,a new constitutive relation considering the evolution of porosity under uniaxial compression was proposed,and the evolution of the porosity was described quantitatively.Then,the effects of constant porosity and evolution porosity on the mechanical behaviors of micro/nanocrystalline Ni with different grain sizes and strain rates were disscussed.