Hua WEI
材料科学技术（英文）
The NiAl phase prepared by pack cementation (PC) on a nickel base superalloy was investigated by X-ray photoelectron spectroscopy (XPS) and positron annihilation technique (PAT). The focus was on the effect of the solid solution of the alloying element from substrate on the binding energy of Ni (Al) 2p peaks and vacancy concentration of the NiAl phase formed in a superalloy. The results showed that the binding energy of Ni 2p peak of the NiAl phase grown in a superalloy was shifted by up to 0.55 eV at the temperature from 850 to 1050℃ towards higher energies and the binding energy of Al 2p peak by up to 1.09 eV in comparison with the NiAl phase formed in pure Ni. The positron lifetimes obtained from the NiAl phase formed in a superalloy were found to be markedly lower than the theoretical values, indicating the decrease in vacancy concentration. The variation of binding energies and vacancy concentration are possibly due to the solid solution of the alloying atoms from the substrate into the NiAl lattice.
关键词:
NiAl phase
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Hua WEI
,
Xiaofeng SUN
,
Qi ZHENG
,
Guichen HOU
,
Hengrong GUAN
,
Zhuangqi HU
材料科学技术（英文）
A numerical method has been developed to extract the composition-dependent interdiffusivity from the concentration profiles in the aluminide coating prepared by pack cementation. The procedure is based on the classic finite difference method (FDM). In order to simplify the model, effect of some alloying elements on interdiffusivity can be negligible. Calculated results indicate the interdiffusivity in aluminide coating strongly depends on the composition and give the formulas used to calculate interdiffusivity at 850, 950 and 1050ºC. The effect on interdiffusivity is briefly discussed.
关键词:
Interdiffusivity
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