摘要
根据优化的激光工艺参数,利用激光冲击处理技术在AZ31B镁合金上制备出纳米结构表层,采用X射线衍射仪(XRD)和透射电镜(TEM)表征了AZ31B镁合金激光冲击处理后表面纳米层的微观结构,分析了纳米晶粒内微挛晶的成因,探讨了激光冲击处理诱导AZ31B镁合金晶粒细化的机理。晶粒细化机理归纳如下:在原始晶粒内,位错滑移导致位错缠结,应力集中诱发机械孪生;在亚晶粒和已经细化的晶粒内,继续形成位错缠结和位错胞;位错缠结转变成小角度取向差的亚晶界,细分粗大晶粒成亚晶粒;亚晶界演变成大角度晶界,最终形成等轴状、取向随机分布的纳米晶组织。
According to the optimized laser parameters, a nanostructured surface layer was fabricated on an AZ31B magnesium alloy by Laser Shock Processing (LSP). The microstructure of the nanocrystalline layer was characterized by means of X-ray diffraction (XRD) and transmission electron microscope (TEM), and the formation reasons of micro-twins as well as a possible grain refinement mechanism were discussed. The grain refinement mechanism is proposed as following: in original grains, dislocation slipping leads to the formation of dislocation tanglings and stress concentration leads to deformation twinning; in the subgrains and refined grains, dislocation tanglings and dislocation cells are formed continuously; dislocation tanglings are transformed into subgrains boundary with low angle, which divides coarse grains into subgrains; subboundaries are gradually developed into grain boundary with high angle, and finally nano-scale grains with equiaxed shape and random orientations are formed.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2014年第4期856-861,共6页
Rare Metal Materials and Engineering
基金
国家自然科学基金资助(50735001
50675089
50975127)
关键词
激光冲击处理
AZ31B
细化机理
位错
孪生
laser shock processing
AZ31B
refinement mechanism
dislocation
twinning