李志强
,
任大刚
,
李斗星
,
郭建亭
金属学报
用原子探针场离子显微镜（AP-FIM）研究了添加B对Ni3Al有序度的影响以及不同Ni／Al比时Ni3Al场离子像衬度的变化无B的Ni3Al样品中晶内出现富Ni区，且随着Ni富集程度的不同而影响场离子像的衬度在.Ni3Al样品中，B的添加会影响Ni3Al晶体的择优取向随B含量的增加，Ni3Al中占据反位置的Al原子增多，有序度降低Ni3Al样品有序度的降低是改善室温延展性的原因之一.
关键词:
Ni_3Al
,
AP-FIM
,
order degree
,
boron
D.G. Ren and X.S. Fan (Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
The purpose of the present work is to study the NiO cluster formation in Ni3Al alloys by field ion microscope and atom probe (AP-FIM). A polycrystal Ni3Al (B-doped) was heat-treated in atmospheres, the surface adsorption of air (hydrogen, oxygen) moisture etc.) occured on the Ni3Al surface and then these absorbents diffused into the interior of alloy through groin boundaries. AP-FIM studies found that the NiO and AlO clusters appeared in the local regions and amount of NiO clusters is much more than that of AlO. Moreover the hydrogen was simultaneously detected in the identical region.These results provided an experimental evidence that the formation of NiO and AlO clusters is the result of reaction of Ni (or Al) with residual moisture in Ni3Al, i.e. Ni+H2 O→NiO+2H. But the samples of B-free Ni3Al and B-doped single crystal Ni3Al have low concentration of NiO and H. This result shows that the diffusion of H2O molecule was promoted by genie boundaries containing boron. In addition, the boron suppresses environmental emvironmental was discussed, which suggested that the formation of Ni-O bonding has influence on bonding character of Ni-Al atoms and benefits the ductility of alloy.
关键词:
Ni-3Al alloy
,
null
,
null
D.G. Ren
,
Z.Q. Li
,
X.S. Fan and J. T. Guo Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China
金属学报(英文版)
By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.
关键词:
intermetallic compound
,
null
,
null
D.G. Ren
,
W.Z. Chen and X.S. Fan ( Laboratory of Atomic Imaging of Solids
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China
,
College of Materials Science and Engineering
,
Fuzhou University
,
Fuzhou 350002
,
China)
金属学报(英文版)
The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (AP-FIM). The samples used have nearly stoichiometric composition of TiAl but there is Mn addition for ingot metallurgy (IM) samples and Mn and Nb additions for CSD samples. The field ion image of TiAl showed two regions of ordered f.c.t crystal structure (γ-TiAl) and disordered α-Ti3Al, and the distribution of Ti and Al atoms in TiAl alloy showed a lamellar structure which was confirmed by AP profiles. AP profiles showed that the major constituent of IM TiAl alloy is γ-TiAl with some Ti-rich regions. The compositions of these Ti-rich regions are nearly Ti3Al and Ti2Al from the calculation of AP data. The sample of CSD has a similar microstructure as compared with IM sample. The effects of alloying elements (Mn and Nb) on the ordering extent ,their distribution, and their sites occupied in the lattice were explored for both TiAl alloys. But there are no obvious Ti3Al or Ti2Al phases as shown in IM sample. In addition, the distributions of Mn and Nb concentrations in the CSD sample have a characteristic of wave form.
关键词:
intermetallic compound
,
null
,
null
