【摘要】 采用超音速微粒撞击工艺在Mg-Gd系稀土变形镁合金材料上成功制备出纳米晶结构表层,通过光学显微镜和高分辨透射电镜研究了由表层沿厚度方向不同变形层区的微观结构特点及微观组织细化特征.结果表明:整个塑性变形层的微观组织和结构呈梯度分布,在样品表层形成了尺寸为10~20 nm晶界清晰的纳米晶粒,亚表层主要为高密度的位错缠结、位错列、位错网络及被位错分割形成的细小残余孪晶或微条带状亚结构,靠近基体的变形层区以形变孪晶和块状亚结构为主.分析认为动态再结晶是细化组织和导致高能亚结构转变为纳米晶粒的最关键因素.更多还原

【Abstract】 A nanostructured surface layer was fabricated successfully in an Mg-alloy of Mg-15Gd-3Y by using a high velocity oxygen-fuel flame supersonic microparticles bombarding(HVOF-SMB) process.The microstructure and its refinement characteristics along the depth of the treated sample surface layer were investigated by optical microscopy(OM) and high-resolution transmission electron microscope(HRTEM).The results show that the homogeneous nano-grains with a grain size of about 10～20 nm are formed in the topmost surface layer.High-density dislocation tangles,dislocation arrays,dislocation networks and the residual twin platelets or residual microbands subdivided by dislocations are found in the subsurface layer.Deformation twins and quadrilateral blocks dominate the plastic deformation zone closed to the matrix.It is believed that the dynamic recrystallization plays a key role in the grain refinement and nano-grains formation.更多还原