TY - JOUR
T1 - Effect of Mn doping on charge density in γ-TiAl by quantitative convergent beam electron diffraction
AU - Holmestad, R.
AU - Zuo, J. M.
AU - Spence, J. C.H.
AU - Hoiert, R.
AU - Horita, Z.
N1 - Funding Information:
This work has been supported by the Facilities of the NSF-ASU Center for HREM at Arizona State University, and by NSF award DMR-9015867 (J.C.H.S., P.I.). J.C.H.S. is grateful for additional support from NFR-NAVF. Jingyue Liu is acknowleged for providing the HB501 EDS analysis and Bgrd Totdal for help with the ALCHEMI analysis. We also thank Dr Knut Marthinsen and Dr Andreas Weickenmeier for valuable discussions. R. Holmestad thanks the Royal Norwegian Council for Scientific
Funding Information:
and Industrial Research for financial support, and the Norwegian Supercomputing Committee (TRU) for support through a grant of computing time.
PY - 1995/9
Y1 - 1995/9
N2 - The intermetallic compound TiAi with and without 5 at.% manganese, has been studied by energy filtered convergent beam electron diffraction (CBED) in a transmission electron microscope. The addition of Mn is known to be beneficial for the mechanical properties of this material. The aim has been to investigate whether this effect is followed by detectable changes in electronic structure, with the focus on bonding. From the positions of high-order Laue zone lines in the centre disc, the lattice tetragonality is found to decrease with the addition of Mn. By ALCHEMI studies, Mn is found to substitute randomly on Ti and Al sites. The structure factors are determined using multiparameter least-square minimization based on fitting between experimental and calculated intensity profiles. The X-ray structure factors for the nine lowest order reflections have been derived for doped and undoped material. The uncertainty is typically 0·3%, and is best for the strong, lowest order reflections. The electron deformation density maps show that the effect of doping with Mn is to draw charge away from nearest-neighbour covalent bonds and redistribute it more uniformly between second nearest neighbours which may enhance ductility.
AB - The intermetallic compound TiAi with and without 5 at.% manganese, has been studied by energy filtered convergent beam electron diffraction (CBED) in a transmission electron microscope. The addition of Mn is known to be beneficial for the mechanical properties of this material. The aim has been to investigate whether this effect is followed by detectable changes in electronic structure, with the focus on bonding. From the positions of high-order Laue zone lines in the centre disc, the lattice tetragonality is found to decrease with the addition of Mn. By ALCHEMI studies, Mn is found to substitute randomly on Ti and Al sites. The structure factors are determined using multiparameter least-square minimization based on fitting between experimental and calculated intensity profiles. The X-ray structure factors for the nine lowest order reflections have been derived for doped and undoped material. The uncertainty is typically 0·3%, and is best for the strong, lowest order reflections. The electron deformation density maps show that the effect of doping with Mn is to draw charge away from nearest-neighbour covalent bonds and redistribute it more uniformly between second nearest neighbours which may enhance ductility.
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U2 - 10.1080/01418619508243787
DO - 10.1080/01418619508243787
M3 - Article
AN - SCOPUS:84953606053
SN - 0141-8610
VL - 72
SP - 579
EP - 601
JO - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
JF - Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties
IS - 3
ER -