硬脆颗粒增强金属基复合材料切削区的变形

在切削力作用下硬脆颗粒增强金属基复合材料内部应力分布不均匀，基体发生弹性变形—塑性变形，增强颗粒发生弹性变形并可能破碎，然后基体夹裹颗粒协调变形并流动．在成屑的层积阶段剪切变形区和层积区中易生裂纹，其后裂纹在切削层中可能沿基体—增强颗粒结合界面扩展、颗粒穿晶解理或破碎、绕过颗粒只在基体中扩展．复合材料的组织和性能，尤其增强颗粒的含量、粒度和与基体的界面结合强度是影响其切削变形的主要因素．

DEFORMATION OF CUTTING ZONE OF THE HARD PARTICLE_ REINFORCED METAL MATRIX COMPOSITES

Under the cutting force, the stress distribution inside the hard particle reinforced metal matrix composites is non_uniform. When elastic_plastic deformation takes place in the matrix, the reinforcing particle suffers elastic deformation only, but it may break, and the matrix then coordinates its deformation with the particle and carries the particle to flow. In the course of layer accumulation of chip, cracks occur easily in both the shear deformation area and the layer accumulation region. As a result, the cracks may propagate along the interface of matrix_reinforcing particle, or intersect the reinforcing particle; they may even keep away the particle and propagate only in the matrix. Thus, the structure and characteristics of composites, especially, the volume fraction and size of reinforcing particle and the interface strength of matrix_particle constitute the main factors determining the propagation way of the cracks and the cutting deformation of composites.