表面机械研磨铝锂合金微观结构及性能变化

Microstructure and Property Variation of Surface Mechanical Attrition Treatment Al-Li Alloy

利用机械研磨技术能够在铝合金表面制备出具有纳米晶体结构特征的表面层。利用金相显微镜、X—射线衍射仪及透射电子显微镜分析研究了表面纳米层的微观组织结构特征,分析纳米化行为及其时硬度的影响。结果表明,经机械研磨处理可使样品表层晶粒细化至纳米级,表面纳米化的程度与塑性变形量有关;其中强烈塑性变形主要发生在表面到距表层100μm深度范围内,在横截面上沿深度方向的晶粒细化程度逐渐减小。与基材相比,表层硬度明显增加。随距表面距离的增加,硬度增加程度越来越小,最终趋于稳定。

On surface of aluminum alloy,a nanostructured surface layer was obtained by using a surface mechanical at- trition(SMA)technique.Microstructure characterization of surface nanocrystallization were characterized by means of metallographic microscope and XRD and TEM.Hardness of the SMA Al-Li alloy was tested by microhardness instru- ment.The grain refinement behavior and the hardness varia- tion are analyzed.Experimental results show that undergo- ing the SMA treatment for a short period of time,the initial coarse-grained structure in the top surface layer was refined into nanostructured,The degree of the surface crystallization is related to the amount of the plasticity deformation.Severe plastic deformation was primarily caused in the region from the surface to about 100μm depth.The size of grains along depth is smaller and smaller from the top surface layer grad- ually to depth.The hardness of the nanostructured layer is enhanced significantly after the SMA treatment compared with that of the coarse-grained material,and the hardness de- creases gradually with an increase in depth.At the same time,the hardness variation tends to steady with the further increase in depth.