Relation between precipitate-free zone width and grain boundary type in 7075-T7 Al alloy
Relation between precipitate-free zone width and grain boundary type in 7075-T7 Al alloy
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DOI：
10.1016/j.actamat.2006.10.015
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发表时间：
2007-03
期刊：
影响因子：
9.4
通讯作者：
B. Cai;B. Adams;T. Nelson
中科院分区：
文献类型：
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作者：
B. Cai;B. Adams;T. Nelson
采用透射电镜和体视学方法研究了7075-T7铝合金摩擦搅拌过程中晶界类型对无沉淀区宽度的影响。在无规晶界处PFZ的平均半宽为70.4±0.7nm。对于小角晶界，在取向差为11°时观察到PFZ半宽的明显转变。对于重合格点（GBS），只有GBS 1、GBS 3和GBS 5的PFZ宽度小于随机格点。采用晶架体视学方法恢复GB平面分布。结果表明，对于大多数的超宽带，超宽带的平面分布是相对各向同性的。低/高指数平面组合观察到大多数的GBS，此外，大多数GBS有倾斜和扭曲的组件。TEM和体视学的综合结果表明，较小的PFZ宽度仅与低的GBs相关，因为在GBs处PFZ的形成和生长除了GBs的几何结构之外还密切依赖于核心结构。
The effect of grain boundary (GB) type on precipitate-free zone (PFZ) width in friction stir-processed 7075-T7 Al alloy is investigated by transmission electron microscopy (TEM) and stereology. The average half width of PFZs at random GBs is 70.4±0.7nm. For low-angle GBs, an apparent transition of PFZ half width is observed at a misorientation of 11°. For coincidence site lattice (Σ) GBs, only Σ1, Σ3 and Σ5 have smaller PFZ width than that of random GBs. Crystal-frame stereology is used to recover the GB plane distribution. It is found that the GB plane distribution is relatively isotropic for most Σ GBs. Low/high index plane combinations are observed for most Σ GBs; furthermore, most Σ GBs have both tilt and twist components. The combined results of TEM and stereology suggest that smaller PFZ width is associated only with low Σ GBs since the formation and growth of PFZs at GBs depends closely on the core structure, in addition to the geometric structure of GBs.