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

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

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

Institute of Physics of Materials X Fr – Cz workshop, Brno, April 2017

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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