铝在纳米纯铁中的低温扩散行为  

Diffusion of aluminum in nanocrystalline iron at lower temperature

作　　者：郝允卫[1] 蒋益明[1] 邓博[1] 钟澄[1] 杨帆[1] 李劲[1] 

机构地区：[1]复旦大学材料科学系,上海200433

出　　处：《材料热处理学报》2008年第5期1-4,8,共5页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(50571027);科技部专项(2005DKA10400);上海市科委纳米专项(0452nm004));上海市重点学科项目资助(B113)

摘　　要：通过表面机械研磨处理（SMAT）技术在纯Fe上制备纳米结构表层。利用X射线衍射（XRD）表征其平均晶粒尺度,使用氢脆技术表征样品表面机械研磨层的微观组织结构,用二次离子质谱仪（SIMS）测量Al在SMAT纯铁纳米结构表层中的扩散性能。结果表明,经过SMAT处理纯Fe表层形成平均尺寸约为31nm的组织。在300-380℃范围内Al在SMAT制备纳米晶Fe中的扩散系数比Al在粗晶纯Fe中扩散系数高6-7个量级。扩散激活能为134kJ/mol,低于传统扩散激活能。扩散性能的提高源于其中具有大量高位错密度的非平衡晶界。By means of surface mechanical attrition treatment（SMAT） to a pure iron plate,a nanometer-grained surface layer was fabricated.The mean average grain size of the surface was characterized by X-ray diffraction（XRD）.The technique of hydrogen embrittlement was employed to characterize the nanocrystalline structure of the surface.The diffusion kinetics of aluminum in the nanocrystalline iron was measured by second ion mass spectrometry at 300～380℃.The results show that the average grain size in the top surface layer is about 31nm,and the diffusivity of Al in the nanocrystalline iron is 6～7 orders of magnitude higher than that in iron lattice.The activation energy of Al diffusion in nanocrystalline iron is 134kJ/mol which is smaller than that for lattice diffusion.The enhanced diffusivity of Al may originate from a large volume fraction of nonequilibrium grain boundaries.

关 键 词：表面纳米化 低温扩散 表面机械研磨处理(SMAT) 

分 类 号：TG156.8[金属学及工艺—热处理] TG174.4[金属学及工艺—金属学]