work hardening of cu-based conductors by deformation under...
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Work hardening of Cu-based conductors bydeformation under cryogenic conditions
Leibniz−Institut
für Festkörper− und
Werkstoffforschung
Dresden
F. Thiel,
J. Freudenberger, A. Kau�mann, D. Rafaja
IFW Dresden, Institut für Metallische Werksto�eHelmholtzstr. 20, 01069 Dresden
TU Bergakademie Freiberg,Institut für Werksto�wissenschaftGustav-Zeuner-Str. 5, 09599 Freiberg
TU Dresden, Institut für Werksto�wissenschaft01062 Dresden
Karlsruher Institut für Technologie,Institut für Angewandte Materialien - Werksto�kunde76128 Karlsruhe
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felix thiel
developmental range of highstrength conductors for pulsedfield magnets
Cu
UTSσ
50 100510
0.5
1.0
1.5
0.5
1.0
1.5
at RTconductivity
[ % IACS ]
[ GPa ]
fatigue strengthafter N=5000
[ GPa ]
[ % ]elongation
High electricalconductivity
(Joule heating)heat capacity
high tensile strength(Lorentz force)
η
σUTS
sufficient ductility(rectangular crosssection and coilwinding)
σUTS
A t
σUTS
% IACS
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strength vs. conductivity
J. Freudenberger High Strength Cu-based conductor Ma-terials, In: Copper Alloys, Nova (2011)
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microstructure of Cu-Ag
hardening mechanisms
I solid solution hardening
I precipitation hardening
I phase boundary hardening
I work hardening
20 40 60 80Ag concentration [ m.-% ]
0
500
1000
Tem
pera
ture
[°C
]
Cu Ag
779.1°C8% 91.2%
961.9°C
1084.9°C
71.9%
(Cu)
(Ag)
S
continuous precipitates(140-160 HV)
discontinuous precipitates(80-100 HV)
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thermo-mechanical treatment
casting
homogenisation850◦C/5h/Ar
rotary swaging750◦Cϕ > 2 for dynamicrecrystallisation
precipitation reaction400◦C/18h/Ar
wire drawingup to ϕ = 4.7
300K
77K
wiredrawingof
pure
copper
activation of an additionalhardening mechanism
I twin boundary hardening
A. Kaufmann, Dissertation, TU Dresden (2014)
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thermo-mechanical treatment
casting
homogenisation850◦C/5h/Ar
rotary swaging750◦Cϕ > 2 for dynamicrecrystallisation
precipitation reaction400◦C/18h/Ar
wire drawingup to ϕ = 4.7
300K
77K
wiredrawingof
pure
copper
activation of an additionalhardening mechanism
I twin boundary hardening
A. Kaufmann, Dissertation, TU Dresden (2014)
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evolution of the microstructureof CuAg5Zr0.3
deformation at room temperature
I mixed <100> <111> �bre texture at large strainsI no formation of deformation twins
100 µm
CuAg5Zr0.3 CuAg5Zr0.3
30 µm
deformation at cryogenic temperature
I mixed <100> <111> �bre texture at large strainsI smaller grains when compared to RT deformationI deformation induced formation of twins
CuAg5Zr0.3
100 µm
CuAg5Zr0.3
30 µm
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evolution of the microstructureof CuAg5Zr0.3
deformation at room temperature
I mixed <100> <111> �bre texture at large strainsI no formation of deformation twins
100 µm
CuAg5Zr0.3 CuAg5Zr0.3
30 µm
deformation at cryogenic temperature
I mixed <100> <111> �bre texture at large strainsI smaller grains when compared to RT deformationI deformation induced formation of twins
CuAg5Zr0.3
100 µm
CuAg5Zr0.3
30 µm
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mechanical and electricalproperties of Cu-Ag5-Zr0.3
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texture in CuAg5Zr0.3 at largedeformation strain
RT deformation CT deformation
.0.480.46
0.32
0.40
[111]
[011]
0.50.49
[001]
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summary & outlook
I deformation under cryogenic condition:I wire drawing of CuAg5Zr0.3 is possibleI texture with mixed <100> <111> �bre texture in wire axisI initiates deformation twins in CuAg5Zr0.3I results in higher strength and lower conductivity when
compared to room temperature deformation
I twin density is lowering at very large deformation strains
I texture evolution not bene�cial for achieving high strength
AcknowledgementFR 1714/2-1
FR 1714/5-1
many thanks to: Enrico Knauer, Dirk Seifert,Hans-Peter Trinks, Sigfried Neumann, MichaelFrey, Kerstin Schröder, Christiane Mix, HansjörgKlauÿ, Tino Wolf and Ludwig Schultz