Structural changes of 9R copper precipitates in an aged Fe-Cu alloy
Structural changes of 9R copper precipitates in an aged Fe-Cu alloy
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DOI：
10.1080/095008300176263
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发表时间：
2000-03-01
影响因子：
1.2
通讯作者：
Jenkins, ML
中科院分区：
文献类型：
--
作者：
Monzen, R;Iguchi, M;Jenkins, ML
利用高分辨透射电镜和常规透射电镜研究了Fe-Co模型合金中孪晶9 R铜沉淀经3R结构向最终稳定结构的转变过程。在尺寸大于约13 nm的9 R沉淀物中，观察到孪晶界的运动和在每三个（009）（9 R）紧密堆积平面上的规则堆垛层错的消除几乎同时发生。直接证据表明，3R是一种非立方结构时，获得的规则堆垛层错的（009）（9 R）基面被删除。在较大的沉淀物（尺寸高达约26纳米）中，3R变体中的晶格平面旋转和平面间距发生变化，趋向稳定的fee和fct结构，这表明发生了涉及原子扩散的晶格弛豫。fct结构的晶格常数a = B = 0.369 nm和c = 0.366 nm比体fee铜（a = 0.361 nm）大。大小为26-40 nm的晶体由几乎与fee和fct相关的双晶变体组成。片段，并根据Kurdjumov-Sachs取向关系与铁基质对齐。观察到较大的沉淀物是fee和fct单晶。
High-resolution transmission electron microscopy and conventional transmission electron microscopy have been used to investigate in detail the transformation processes of twinned 9R copper precipitates to final stable structures via a 3R structure in a thermally aged Fe-Co model alloy. In 9R precipitates of size greater than about 13 nm, the motion of the twin boundaries and the elimination of the regular stacking faults on every third (009)(9R) close packed plane were observed to occur nearly simultaneously. Direct evidence was found that 3R is a non-cubic structure obtained when the regular stacking faults on the (009)(9R) basal planes are removed. In larger precipitates (of size up to about 26 nm), lattice plane rotations and plane spacing changes in 3R variants took place towards stable fee and fct structures, suggesting the occurrence of lattice relaxation involving the diffusion of atoms. The fct structure had larger lattice constants a = b = 0.369 nm and c = 0.366 nm than bulk fee copper (a = 0.361 nm). Precipitates of;size 26-40 nm consisted of nearly twin-related variants with both fee and fct. segments, and aligned with the iron matrix according to the Kurdjumov-Sachs orientation relationship. Larger precipitates were observed to be fee and fct single crystals.