1. Research on fatigue of materials at IPM
Tomáš Kruml
Institute of Physics of Materials
Czech Academy of Sciences
Fr – Cz workshop, Brno, April 2017

2. Outline one slide about Czech Academy of Sciences
two slides about Institute of Physics of Materials
two slides about Fatigue Laboratories
example: twinning in TiAl during cyclic deformation
Fr – Cz workshop, Brno, April 2017

3. Czech Academy of Sciences
Non-university research organization (similar to CNRS)
52 research institutes (physics, life sciences, humanities…)
~ 8500 employees
Relevant institutes for materials research:
Inst. of Physics, Prague (Fejfar)
Inst. of Physics of Materials, Brno (Kruml, Gröger)
Nuclear Physics Inst., Řež – Prague, (Hervoches)
Inst. of Plasma Physics
Fr – Cz workshop, Brno, April 2017

4. Institute of Physics of MaterialsX
Fr – Cz workshop, Brno, April 2017

5. Institute of Physics of Materials
~ 140 employees (FTE)
½ researchers + Ph.D. students
Dept. of Mechanical Properties
Dept. of Structure
Advanced high T materials (creep)
Low cycle fatigue
High cycle fatigue
Brittle fracture
Structure of phases & thermodynamics
Electrical & magnetic properties
Fr – Cz workshop, Brno, April 2017

6. Fatigue at IPM Long tradition! (50 years)
TEM observation od PSBs (Lukáš, 1968)
Physical model of PSBs (Polák, 1987)
Theory of short crack growth rate
Statistical theory of hysteresis loop
Fatigue damage mechanisms in advanced
materials
Fr – Cz workshop, Brno, April 2017

7. Fatigue at IPM Two groups (Low cycle fatigue, High cycle fatigue)
~ 15 researchers, 11 Ph.D. students
5 servohydraulic machines (axial/torsional, thermomechanical, up to 1200 °C)
7 resonant machines
gigacycle test machine
MTS Tytron 250N
Fr – Cz workshop, Brno, April 2017

8. Twinning in TiAl TiAl alloys (~Ti50Al50) Advantages
low density (r=1/2 of steel, superalloys)
high strength at high temperatures
good corrosion resistance
Critical issues
low fracture toughness at RT
large scatter in properties
restricted machinability
inhomogeneities after casting
TiAl Wastegate
TiAl Sport Cast Turbine Housings
GEnxTM engine with TiAl blades (Boeing 787)
Fr – Cz workshop, Brno, April 2017

9. Twinning in TiAl Improvement of properties:
1. Tailoring the microstructure
fully lamellar (fracture toughness, creep strength)
nanolamellar
duplex (ductility)
near gamma
massive transformation
textured alloys (defining the orientation of lamellae) …
2. Additional elements
Nb, Mo, Cr, Mn, Si, Ta, W, B, Zr, C …
Fr – Cz workshop, Brno, April 2017

10. Twinning in TiAl Ti – 48Al – 2Nb – 2Cr – 0.8B near g microstructure
60 mm grain size
symmetric cycling RT
ea = const.
Fr – Cz workshop, Brno, April 2017

11. Twinning in TiAl : TEM TEM study: twinning & dislocation activity
Fr – Cz workshop, Brno, April 2017

12. Twinning in TiAl : TEM TEM study: crystallography, origin of twinning
ITER construction, 9/2015
Fr – Cz workshop, Brno, April 2017

13. Twinning in TiAl : TEM ITER construction, 9/2015
Fr – Cz workshop, Brno, April 2017

14. Twinning in TiAl : in situ neutron diffraction
+ Přemysl Beran (Nuclear Physics Institute)
+ Tobias Panzner, Steven van Petegem (Paul Scherrer Inst., Viligen, CH)
Fr – Cz workshop, Brno, April 2017

15. Twinning in TiAl : in situ neutron diffraction
Fr – Cz workshop, Brno, April 2017

16. Twinning in TiAl : in situ neutron diffraction
Fr – Cz workshop, Brno, April 2017

17. Twinning in TiAl : acoustic emission
+ Alexei Vinogradov (Univ. Trondheim, univ. Togliatti)
+ Kristian Mathis (Charles univ., Prague)
Fr – Cz workshop, Brno, April 2017

18. Twinning in TiAl : acoustic emission
Fr – Cz workshop, Brno, April 2017

19. Summary TEM In-situ neutron diffraction In-situ acoustic emission
deformation modes (twinning, dislocation structures)
microstructural parameters
(twin thickness, dislo density, ...
In-situ neutron diffraction
lattice strain development due to twinning
twinning activity in first cycles
In-situ acoustic emission
twins are not quite stable and may detwin upon reverse loading
some twins which have been formed in tension detwin in compression
twins are produced undoubtedly on both tensile and compressive hall-loops though with different rate.
Fr – Cz workshop, Brno, April 2017