Microstructure and texture evolution during annealing a cryogenic-SPD processed Al-alloy with a nanoscale lamellar HAGB grain structure
Microstructure and texture evolution during annealing a cryogenic-SPD processed Al-alloy with a nanoscale lamellar HAGB grain structure
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DOI：
10.1016/j.actamat.2009.04.010
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发表时间：
2009-07
期刊：
影响因子：
9.4
通讯作者：
G. H. Zahid;Yan Huang;P. Prangnell
中科院分区：
文献类型：
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作者：
G. H. Zahid;Yan Huang;P. Prangnell
用透射电镜和电子背散射衍射研究了Al-0.13%Mg亚微米晶合金在低温平面应变压缩（PSC）变形后退火过程中的晶粒结构和织构演变。变形后的合金包含一个层状晶粒结构，大角度晶界（HAGB）间距为190 nm，面积分数为1.80%。退火时，晶粒组织粗化，由片层状向等轴晶转变。值得注意的是，在退火过程中，小角度晶界（LAGB）的比例逐渐增加，在300°C以上达到约50%，导致在更高温度下的不稳定性和不连续再结晶。这导致了一个“双峰晶粒结构”的粗晶粒和细亚晶粒的乐队组成的，由于低流动性LAGB的比例增加而产生的。退火时LAGB分数令人惊讶的大幅度增加被证明与取向冲击有关，这源于液氮中PSC后存在的强织构。
The grain structure and texture evolution during annealing a Al–0.13% Mg submicron-grained alloy, deformed by plane-strain compression (PSC) at cryogenic temperatures, has been investigated by transmission electron microscopy and electron backscatter diffraction. After deformation the alloy contained a lamellar grain structure with a high-angle grain boundary (HAGB) spacing of 190nm and an area fraction of ∼80%. On annealing the grain structure coarsened and transformed from lamellar to equiaxed. Remarkably, the fraction of low-angle grain boundaries (LAGBs) progressively increased during annealing, to ∼50% above 300°C, leading to instability and discontinuous recrystallization at higher temperatures. This resulted in a “bimodal grain structure” comprised of bands of coarser grains and fine subgrains, arising as a result of the increase in proportion of lower-mobility LAGBs. The surprisingly large increase in LAGB fraction on annealing is shown to be related to orientation impingement, originating from the strong texture present after PSC in liquid nitrogen.