Metastable phases in bulk intermetallic compounds

Metastable phases in bulk intermetallic compounds - dedicated structural characterization based on transmission electron microscopy

Severe plastic deformation of intermetallic compounds can be used to make metastable phases. The resulting metastable phases being far away from the thermodynamic equilibrium often exhibit properties that are superior to those of the corresponding crystalline or equilibrium phase. Consequently, metastable phases are a timely exciting research topic of materials science and there is a strong impetus to obtain a comprehensive understanding of the fundamental factors controlling the transformations and the stability of these new phases.

It is the purpose of the FWF project [P22440-N20] to gain experimental findings of the formation, structure, properties and stability of deformation induced metastable phases in bulk intermetallic compounds. Mainly, L1₂ long-range ordered alloys (Zr₃Al, Co₃Ti) and B2 long-range ordered alloys (FeAl, CoTi) will be studied. The metastable polymorphous phases will be produced using high-pressure torsion and accumulative roll bonding. Within the framework of the project the following innovative aspects will be studied:

the evolution and the characterization of the different metastable structures,

the fundamental deformation mechanisms in nanocrystalline intermetallics,

the cyclic occurrence of the amorphous phase in CoTi and Co₃Ti during SPD,

the thermal stability and recovery processes of the metastable structures.

In order to achieve these challenging goals innovative experiments with well designed parameters will be carried out (e.g.: re-deformation of different nanocrystalline structures, re-ordering under different hydrostatic pressures). The systematic experimental standards will be based on TEM investigations including atomic resolution TEM and a spectrum of complementary experimental methods (e.g.: differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction).

The well-designed systematic study will lead to new experimental findings facilitating a deeper understanding of the fundamentals of deformation-induced metastable phases. These results can pave the way to design novel composite materials consisting of different metastable phases (e.g.: ordered coarse-grained and disordered nanocrystalline; nanocrystalline and amorphous) made by controlled severe deformation to tailor their properties.

Funder: Austrian Science Fund

Project identifier:

Principal investigator: Christian Rentenberger

Publications

Anomalous re-ordering of Fe3Al disordered by high pressure torsion deformation
C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger
Scripta Mater 156 (2018) 90-94.
[doi: 10.1016/j.scriptamat.2018.06.043]

Reordering a deformation disordered intermetallic compound by antiphase boundary movement
C. Gammer, H. P. Karnthaler, C. Rentenberger
J. All. Comp. 713 (2017) 148-155.
[doi: 10.1016/j.jallcom.2017.04.045]

Anomalous beam effects during in situ transmission electron microscopy deformation of nanocrystalline and ultrafine-grained metals
R. Sarkar, C. Rentenberger, J. Rajagopalan
Microsc. Microanal. 22 (Suppl 3), 1498-1499 (2016)
[doi: 10.1017/S1431927616008333][pdf]

TEM analysis of deformation induced nanocrystallisation in an amorphous CoTi alloy
S. Noisternig, C. Ebner, C. Gammer, C. Rentenberger, C. Gspan, H.P. Karnthaler
Proc. Europ. Micr. Conf. 2016, Lyon, France (2016).
[doi: 10.1002/9783527808465.EMC2016.5361] [pdf]
[emc-proceedings.com]

Electron beam induced artifacts during in situ TEM deformation of nanostructured metals
R. Sarkar, C. Rentenberger, J. Rajagopalan
Sci. Rep. 5 (2015) 16345.
[doi:10.1038/srep16345]
[phaidra.univie.ac.at/o:454084]

Sessile dislocations by reactions in NiAl severely deformed at room temperature
D. Geist, C. Gammer, C. Rentenberger, H. P. Karnthaler
J. All. Comp. 621 (2015) 371-377
[doi: 10.1016/j.jallcom.2014.09.226]

Unexpected grain size reduction by heating in bulk nanocrystalline FeAl
C. Gammer, H. P. Karnthaler, C. Rentenberger
J. All. Comp., 633 (2015) 384-389.
[doi:10.1016/j.jallcom.2015.01.186] [preprint]

Quantitative TEM analysis of the grain size in a nanocrystalline alloy
C. Gammer, C. Rentenberger, H. P. Karnthaler
Proc. Multinational Congress on Microscopy (Eger, Hungary) 74 (2015).

Nanocrystals in amorphous Co3Ti studied by transmission electron microscopy methods
S. Noisternig, C. Ebner, C. Gammer, C. Rentenberger, H. P. Karnthaler
Proc. Multinational Congress on Microscopy (Eger, Hungary) 503 (2015).

Analysis of nanocrystals embedded in Co3Ti made amorphous by severe plastic deformation
S. Noisternig, C. Ebner, C. Gammer, C. Rentenberger, C. Gspan, F. Hofer, H. P. Karnthaler
Proc. Intern. Microsc. Conf. 2014, Prague, Czech Rep.
[pdf]

Quantitative local structure analysis of nanocrystalline FeAl by electron diffraction
C. Rentenberger, C. Gammer, H. P. Karnthaler
Proc. Intern. Microsc. Conf. 2014, Prague, Czech Rep.
[pdf]

Statistical analysis of nanocrystals embedded in the amorphousphase of a Co-Ti alloy studied by TEMS. Noisternig, C. Gammer, D. Geist, H. P. Karnthaler and C. RentenbergerProc. Micr. Conf. 2013, Regensburg, 660 (2013).[pdf]

Devitrification of Co₃Ti studied by in-situ heating in the TEM
C. Ebner, C. Gammer, D. Geist, H. P. Karnthaler, C. Rentenberger
Proc. Micr. Conf. 2013, Regensburg, 664 (2013).
[pdf]

TEM study of Co3Ti made amorphous by high pressure torsion
C. Gammer, D. Geist, H. P. Karnthaler, C. Rentenberger
Proc. Micr. Conf. 2013, Regensburg, 690 (2013).
[pdf]

Radiation effects in bulk nanocrystalline FeAl alloy
A. Kilmametov, A. Balogh, M. Ghafari, C. Gammer, C. Mangler, C. Rentenberger, R. Valiev, H. HahnRadiation Effects and Defects in Solids 167, 631-639 (2012).
[doi:10.1080/10420150.2012.666241]

Nanocrystalline Zr3Al made through amorphization by repeated cold rolling and followed by crystallization
D. Geist, S. Ii, K. Tsuchiya, H. P. Karnthaler, G. Stefanov, C. Rentenberger
J. Alloys and Comp. 509, 1815 (2011).
[doi:10.1016/j.jallcom.2010.10.050] [preprint pdf]

Thermally induced transition from a ferromagnetic to a paramagnetic state in nanocrystalline FeAl processed by high-pressure torsion
C. Mangler, C. Gammer, K. Hiebl, H.P. Karnthaler, C. Rentenberger
J. Alloys and Comp. 509, Suppl. 1, 389 (2011).
[doi:10.1016/j.jallcom.2010.12.023] [preprint pdf]

Three-dimensional analysis by electron diffraction methods of nanocrystalline materials
C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger
Micoscopy and Microanalysis 17, 866-871 (2011).
[doi:10.1017/S1431927611011962 ] [preprint pdf]

Growth of nanosized chemically ordered domains in intermetallic FeAl made nanocrystalline by severe plastic deformation
C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger
Scripta Mater. 65, 57 (2011).
[doi:10.1016/j.scriptamat.2011.03.002] [preprint pdf]

Extreme structural inhomogeneities in high pressure torsion samples along the axial direction
D. Geist, C. Rentenberger, H. P. Karnthaler
Acta Mater 59, 4578 (2011).
[doi:10.1016/j.actamat.2011.04.003 ] [preprint pdf]

Dislocation plasticity of Al film on polyimide investigated by cross sectional in-situ TEM straining
S. H. Oh, C. Rentenberger, C. Motz, J. Im, D. Kiener, H. P. Karnthaler, G. Dehm
Scripta Mater. 65, 456 (2011).
[doi:10.1016/j.scriptamat.2011.06.001 ] [preprint pdf]

Modifications of the physical properties of semiconducting MgAl2O4 by doping with a binary mixture of Co and Zn ions
M. J. Iqbal, B. Ismail, C. Rentenberger, H. Ipser
Mater. Res. Bull., 46, 2271-2277 (2011).
[doi:10.1016/j.materresbull.2011.08.061]

TEM investigations of bulk nanocrystalline intermetallics in 3D
C. Gammer, D. Geist, C. Mangler, H. P. Karnthaler, C. Rentenberger
Proc. of the Multinational Congress on Microscopy 2011, Societa Italiana Scienza Micriscopiche Ancona, Italy, 603-604 (2011).
[pdf]

PASAD-tools, a software for quantitative analysis of SAD patterns
C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger
Proc. of the Multinational Congress on Microscopy 2011, Societa Italiana Scienza Micriscopiche Ancona, Italy, 35-36 (2011).
[pdf]

Structural analysis of severely deformed Ni₃Ge by electron microscopy methods
A. Grill, H. P. Karnthaler, C. Rentenberger
Proc. of the Multinational Congress on Microscopy 2011, Societa Italiana Scienza Micriscopiche Ancona, Italy, 609-610 (2011).
[pdf]

Combining TEM diffraction and imaging for a complete structural analysis of bulk nanocrystalline materials using example of FeAl
C. Gammer, C. Mangler, H. P. Karnthaler, C. Rentenberger
Proc. of the Microscopy Conference Kiel, DGE (ISBN 978-3-00-033910-3), M5-535 (2011).

Quantitative local profile analysis of nanomaterials by electron diffraction
C. Gammer, C. Mangler, C. Rentenberger and H. P. Karnthaler
Scripta Mater. 63, 312 (2010).
[doi:10.1016/j.scriptamat.2010.04.019].
http://www.univie.ac.at/pasad/
[preprint pdf]

In situ TEM study of microplasticity and Bauschinger effect in nanocrystalline metals
J. Rajagopalan, C. Rentenberger, H. P. Karnthaler, G. Dehm, M. T. A. Saif
Acta Mater. 58, 4772 (2010).
[doi:10.1016/j.actamat.2010.05.013].

Electron Microscopy of severely deformed L12 Intermetallics
D. Geist, C. Gammer, C. Mangler, C. Rentenberger, H. P. Karnthaler
Phil. Mag. 90, 4635 (2010).
[doi:10.1080/14786435.2010.482178 ] [preprint pdf]

Structural modifications during heating of bulk nanocrystalline FeAl produced by high pressure torsion
C. Mangler, C. Gammer, H. P. Karnthaler, C. Rentenberger
Acta Mater. 58, 5631 (2010).
[doi:10.1016/j.actamat.2010.06.036 ] [preprint pdf]