Shen Qin, Chen Hao, Liu Wenqing
1Key Laboratory for Microstructures,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,People's Republic of China.
2Key Laboratory for Advanced Materials of Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,People's Republic of China.
Microsc Microanal. 2017 Apr;23(2):350-359. doi: 10.1017/S1431927616012599. Epub 2017 Mar 21.
The microstructural evolution of precipitation in two model alloys, Fe-NiAl and Fe-NiAl-Cu, was investigated during aging at 500°C for different times using atom probe tomography (APT). The APT results reveal that the addition of Cu effectively increases the number density of NiAl precipitates. This is attributed to Cu promoting the nucleation of NiAl particles by increasing the chemical driving force and decreasing the interfacial energy. The NiAl precipitates of the Fe-NiAl-Cu alloy grow and coarsen at a slower rate than that of the Fe-NiAl alloy, mainly due to the slower diffusion rate of the Cu atoms. The mechanical properties of the two alloys were characterized by Vickers hardness and tension tests. It was found that the addition of Cu results in the formation of core-shell precipitates with a Cu-rich core and a NiAl shell, leading to a dramatic improvement of peak hardness and strength. The effect of Cu on precipitation strengthening is discussed in terms of chemical strength and coherency strength.
利用原子探针断层扫描技术（APT），研究了两种模型合金Fe-NiAl和Fe-NiAl-Cu在500°C下不同时效时间的析出物微观结构演变。APT结果表明，添加Cu有效地增加了NiAl析出物的数量密度。这归因于Cu通过增加化学驱动力和降低界面能促进了NiAl颗粒的形核。Fe-NiAl-Cu合金的NiAl析出物生长和粗化速度比Fe-NiAl合金慢，主要是由于Cu原子的扩散速度较慢。通过维氏硬度和拉伸试验对两种合金的力学性能进行了表征。发现添加Cu导致形成富Cu核心和NiAl外壳的核壳析出物，从而显著提高了峰值硬度和强度。从化学强度和相干强度方面讨论了Cu对析出强化的影响。
