Three-dimensional atom probe microscopy study of interphase precipitation and nanoclusters in thermomechanically treated titanium-molybdenum steels
Three-dimensional atom probe microscopy study of interphase precipitation and nanoclusters in thermomechanically treated titanium-molybdenum steels
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DOI：
10.1016/j.actamat.2013.01.028
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发表时间：
2013-04-01
期刊：
影响因子：
9.4
通讯作者：
Hodgson, P. D.
中科院分区：
文献类型：
--
作者：
Mukherjee, S.;Timokhina, I. B.;Hodgson, P. D.
原子探针显微镜被用于在模拟带钢轧制条件下对添加Ti - Mo的微合金钢中溶质聚集和沉淀反应进行断层分析。观察到，施加预应变后沉淀物的相间行间距减小。原子探针数据还显示，即使在等温保持3600秒后，纳米团簇和沉淀颗粒仍然共存。这些微观结构特征既出现在三维相间沉淀片内，也出现在随机选取的视场中。在相间片/行内，较大（约8 - 10 nm）的沉淀物与较小的纳米团簇（约3 nm）呈双峰分布共存。纳米团簇和沉淀物都具有圆盘状形态，尽管原子数少于约30个的纳米团簇形状更不规则。纳米团簇和沉淀物的大小用 Guinier半径表示，在两种应变条件下，其大小在0.5到8 nm之间变化，平均大小约为1.8 nm。纳米团簇的成分变化范围很广，但大多富含C。所有纳米团簇和沉淀物都由Ti、Mo和C混合组成，平均沉淀物成分接近MC碳化物化学计量比，其中M代表Ti和Mo的混合物。在大多数情况下，MC碳化物中的Ti/Mo比>1。当Guinier半径增加到2.5 nm以上时，成分范围变窄，趋近于MC碳化物化学计量比，同时含有少量Fe（约3 - 12 at.%）。（C）2013 Acta Materialia Inc. 由Elsevier Ltd.出版。保留所有权利。
Atom probe microscopy was used to generate tomographic analyses of solute clustering and precipitation reactions in a Ti-Mo added microalloyed steel under simulated strip-rolling conditions. It was observed that the interphase row spacing of precipitates was reduced with the application of a pre-strain. The atom probe data also revealed the coexistence of nanoclusters and precipitate particles, even after isothermal holding for 3600 s. These microstructural features occurred both within 3-D interphase precipitate sheets, and in randomly selected fields of view. A bimodal distribution of larger (similar to 8-10 nm) precipitates coexisted with smaller nanoclusters (similar to 3 nm) within the interphase sheets/rows. Both the nanoclusters and the precipitates possessed a disc morphology, although nanoclusters with less than similar to 30 atoms were more irregular in shape. The size of the nanoclusters and the precipitates was expressed as a Guinier radius, and this varied between 0.5 and 8 nm for both strain conditions, with the average size similar to 1.8 nm. The composition of the nanoclusters varied over a wide range, yet was mostly rich in C. All of the nanoclusters and precipitates consisted of a mixture of Ti, Mo and C and the average precipitate composition was close to that of MC carbide stoichiometry, where M represents a mixture of Ti and Mo. In the majority of cases, the Ti/Mo ratio in the MC carbides was > 1. As the Guinier radius increased above 2.5 nm, the composition range became narrower, towards the MC carbide stoichiometry, with a small amount of Fe (similar to 3-12 at.%). (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.