基于应变梯度位错理论的纳晶-无定形态层状复合材料的力学性能研究

纳晶-无定形态层状复合材料具有高强度高硬度还有良好的韧性等力学性能。为了定量评估这种新型材料的力学性能,建立了基于位错密度和应变梯度的力学模型。即在塑性变形的初始阶段,位错在晶态-非晶态层的交界面处产生,之后通过滑移穿过纳晶层到达对面的晶态-非晶态的交界面处被吸收。鉴于纳晶层和无定形态层的不同特性和界面的相互作用,理论分析了纳晶层中的位错演化过程以及交界面的损伤情况。结果表明,理论计算与实验结果基本吻合,且纳晶层无定形态之间的交界面具有很好的变形协调能力而不会在界面层产生失效。

MECHANICAL BEHAVIORS OF CRYSTALLINE-AMORPHOUS NANOLAMINATES BASED ON STRAIN GRADIENT DISLOCATION THEORY

Crystalline-amorphous nanolaminates exhibit superior mechanical properties such as high strength and good ductility. For quantitative analysis the mechanical behaviors of crystalline-amorphous nanolaminate, a model based on the special statistically stored dislocations density and strain gradient was proposed. At the outset of the plastic deformation, dislocations are nucleated from the crystalline-amorphous interfaces. Then, dislocations glide across the crystal layer and are absorbed by the opposite crystalline-amorphous interface. Due to the different properties and interplay between the crystalline phase and amorphous phase, the corresponding dislocation evolution behavior in crystalline phase and the interface failure was analyzed. The calculation results are in agreement with experimental results and the interface of crystalline-amorphous nanolaminate can avoid stress concentrations that lead to fracture failure.