摘要
利用透射电镜和高分辨透射电镜(HRTEM)研究了高压扭转大塑性变形纳米结构Al–Mg合金中的位错和晶界结构。结果表明:对尺寸小于100 nm的晶粒,晶内无位错,其晶界清晰平直;而尺寸大于200 nm的大晶粒通常由几个亚晶或位错胞结构组成,局部位错密度可高达1017m-2,这些位错往往以位错偶和位错环的形式出现。用HRTEM观察到了小角度及大角度非平衡晶界、小角度平衡晶界和大角度Σ9平衡晶界等不同的晶界结构。基于实验结果,分析了局部高密度位错、位错胞和非平衡晶界等在晶粒细化过程中的作用,提出了高压扭转Al–Mg合金的晶粒细化机制。
The structure of dislocation and grain boundary(GB) in nanostructured Al–Mg alloys processed by high pressure torsion(HPT) was characterized by means of transmission electron microscopy(TEM) and high-resolution TEM(HRTEM).The results show that the grains less than 100 nm have sharp GBs and are completely free of dislocations.In contrast,a high density of dislocation as high as 1017m- 2 exists within the grains larger than 200 nm and these larger grains are usually separated into subgrains and dislocation cells.These dislocations appear as dipoles and loops.Different GB structures including low/high angle non- equilibrium GBs,low angle equilibrium GBs and high angle Σ 9 equilibrium boundaries are characterized by HRTEM.The roles of the very high local dislocation density,the dislocation cells and the non-equilibrium GBs in grain refinement during HPT are analyzed and the refinement mechanisms associated with these structural features have been proposed.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2014年第5期371-379,共9页
Chinese Journal of Materials Research
基金
国家自然科学基金50971087
江苏省自然科学基金BK2012715
江苏大学高级人才启动基金11JDG070&11JDG140
江苏省高端结构材料重点实验室资金hsm1301
江苏省材料摩擦学重点实验室基金Kjsmcx2011004资助项目~~
关键词
金属材料
高压扭转
大塑性变形
铝合金
晶界结构
非平衡晶界
位错
metal materials,high pressure torsion,severe plastic deformation,aluminium alloys,grain boundary structure,non-equilibrium grain boundary,dislocation
