用Ｘ射线衍射及透射电镜研究用惰性气体凝聚法制备纳米ＮｉＡｌ合金固体的结构结果表明，纳米ＮｉＡｌ合金晶体结构与常规ＮｉＡｌ结构一致，平均粒度为８．６ｎｍ，具有较大的晶格（显微）畸变（ε＝１．２％），长程有序度有所降低。退火实验显示，当温度低于８００Ｋ时晶粒不明显长大，具有较好的抗晶粒生长能力。磁共振及磁化研究表明，当ＮｉＡｌ合金制成纳米结构后由弱（或非）磁性转变为强磁性，这种磁性转变可能与具较大的晶格畸变及长程有序度的破坏有关。
The structure of nanostructured NiAl(n-NiAl), synthesized by inert-gas condensation, was investigated by X-ray diffraction and TEM. The results indicated that the crystal structure of n-NiAl is same as that of conventional poly-crystalline NiAl alloy(p-NiAl); and the mean grain size of n-NiAl is 8.6 nm. However, there is severe distortion in the crystal lattice of n- NiAl(the distortion ε = 1 .2%); and the long-range ordering degree of n-NiAl is lower than that of p-NiAl. Annealing experiments showed that the grain growth almost did not occur when annealing temperature was lower than 800 K, indicating that n-NiAl is of high resistance to grain growth. In addition, by using electron-spin resonance and magnetization, the strong magnetism(ferro-or antiferromagnetism) of n-NiAl has been ovserved, and it is different from the conventional p-NiAl with weak one. The enhancement of magnetism of n-NiAl would be related to the severe distortion in the crystal lattice and the damage of long-range ordering degree of n-NiAl. Correspondent: QIN Xiaoying, associate professor, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031
参考文献
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