APFIM investigations on site preferences, superdislocations, and antiphase boundaries in NiAl(Cr) with B2 superlattice structure

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• 作者：Fischer ; R. ; Frommeyer ; G. ; Schneider ; A.
• 关键词：NiAl(Cr) ; Atom probe field ion microscopy ; Antiphase boundary ; Superdislocation ; 61.72.Ff ; 61.72.Ss ; 68.35.Dv ; 68.37.Vj
• 刊名：Materials Science and Engineering ; A
• 出版年：2003
• 期刊代码：61_09215093
• 类别：ms
• 出版时间：July 25, 2003
• 卷：353
• 期：1-2
• 页码：87-91
• 文件大小：323 K

摘要

The effect of the ternary element chromium in B2 ordered NiAl based alloys was studied by atom probe field ion microscopy. Samples of the compositions Ni₅₀Al₄₈Cr₂, Ni₄₉Al₄₉Cr₂, and Ni₄₈Al₅₀Cr₂ were investigated after different heat treatments. The chromium concentrations of the NiAl matrix, measured by atom probe, increased with increasing Ni/Al ratio and heat treatment temperature. The site preference of solute Cr atoms for the Al sublattice was determined by layer resolved measurements. An antiphase boundary observed in Ni₅₀Al₄₈Cr₂ showed a high local Cr concentration with Cr atoms substituting for Al atoms. Superdislocations in the quasi-stoichiometric Ni₄₉Al₄₉Cr₂ were not dissociated into partial dislocations and showed no Cr segregation. These results are discussed in view of activation of a111 slip systems.