内生晶体非晶合金复合材料变形场演化与剪切带行为

通过数字图像相关方法从实验上观察到内生晶体复合材料在微米尺度应变场的演化与剪切带行为,并结合有限元,模拟了非晶合金复合材料的变形,给出了应力应变场的分布,分析了两相在变形中的作用.实验与有限元结果表明,在宏观弹性段内,晶体相会优先发生塑性变形,而后在界面形成应变集中,逐渐向周围扩展;随着加载的进行,材料内部形成变形局部化剪切带.非晶合金复合材料的塑性变形主要由剪切带贡献,而晶体相的存在促进了多重剪切带的形成;复合材料的载荷则主要由连续的非晶基体相承担,剪切带形成伴随自由体积的快速增加,导致非晶基体流动应力下降,复合材料承载能力降低.

Deformation field evolution and shear banding of an in-situ crystal reinforced amorphous alloy composite

The strain field and shear band behaviors of an in-situ crystal reinfored amorphous alloy composite at microscale were experimentally characterized by digital image correlation method.Combined with the finite element analysis,the deformation of the amorphous alloy composite was simulated,and the evolution of stress and strain fields was given out.The role of each phase during the deformation was analysed.The results show that in the macroscopically elastic range,the crystal phase first deformed plastically,then strain concentration formed at the phase interface,and gradually expanded to the surrounding.As the applied strain increased,strain localization occured inside the material.It is found that,the plastic deformation of the composites is accommodated by shear bands,and the presence of crystal phase in the amorphous alloy composite promotes the formation of multiple shear bands.The load of the composite is mainly sustained by the continuous amorphous matrix,and the shear band forms along with a rapid increase of free volume,which leads to a decrease of flow stress and subsequent a reduced loadbearing capacity of the composite.