Neutron scattering contribution to development of modern materials

Transcription

1 Neutron scattering contribution to development of modern materials P. Strunz 1, R. Gilles 2, D. Mukherji 3, M. Petrenec 4, M. Hofmann 2, V. Davydov 5, U. Gasser 5, P. Beran 1, M. Hölzel 6 and J. Rösler 3 1 Nuclear Physics Institute ASCR, CZ Řež near Prague, Czech Republic, Czech Republic 2 TU München, Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstraße 1, Garching, Germany 3 TU Braunschweig, Institut für Werkstoffe, Langer Kamp 8, Braunschweig, Germany 4 IPM Brno, Czech Republic 5 Paul Scherrer Institute, CH-5232 Villigen, Switzerland 6 TU Darmstadt, Materialwissenschaft, Petersenstraße 23, Darmstadt, Germany Acknowledgements: DFG Forschergruppe 727 (Beyond Ni-Base Superalloys) and PPP project CZ13-DE06/ (DAAD-AVCR project ID , High temperature in-situ neutron diffraction on CoRe alloys). 1

2 Metallic and ceramic materials: What can be investigated? Structure and microstructure Phase transformations (e.g. martensitic in SMA) Phase content Residual stresses in depth Microstresses, dislocation density, grain size Precipitates in alloys, particle dispersions Precipitate formation/dissolution Nanoscaled materials, nanoparticles Porosity Interfaces and surfaces of catalysts, semipermeable membranes In-situ tests at operational conditions Non-destructive testing 2

3 Outline Examples neutron diffraction use for study of several metallic materials Single crystal superalloy (SANS) ZrO 2 Thermal Barrier Coating (SANS) Al-Pb system (SANS) CoRe high temperature alloys (ND) Porous metallic membrane (SANS) Inconel superalloy (SANS) 3

4 Superalloys 4

5 Materials for high-temperature (HT) applications 1. processed before the use at HT 2. used at high-temperatures => investigation of HT (micro)structure Energy industry Efficiency (temperature driven) Ni-base superalloys Excellent strength, creep resistance Two-phase microstructure: g-phase matrix strengthened by g precipitates (size nm-mm) optimized by heat treatment essential for mechanical properties Composition: e.g. Cr 8.0, Co 4.0, Mo 0.5, Al 5.7, W 9.0, Ti 0.7, Ta 5.7, Ni balance; in wt% 5

6 z (mm) z (mm) Q y Examples [100] a b c d [320] single-crystal superalloys size: 1030 Å distance: 1114 Å weight: size: 1797 Å distance: 1881 Å size: 2564 Å distance: 2649 Å Q x (Å -1 weight: weight: ) Q x (Å ) x (mm) x (mm) x (mm) 3.0 size distribution in one block: size distributions XZ section XY section old model, volume mean size weighted Å gray scale map: measured data equiintensity lines: fit new model, mean size 2030 Å a d x (mm) x (mm) size (Å) 6

7 volume distribution (dimensionless) Q y Q y T=23 C T=850 C T=1080 C T=1120 C 0mm 1mm 2mm 3mm T=1160 C T=1200 C T=1300 C T=1340 C 6.6E4-1.4E5 3.2E4-6.6E4 1.6E4-3.2E4 7.6E3-1.6E4 3.7E3-7.6E3 1.8E3-3.7E E Q x Q x Q x Q x Superalloy SCA433 High temperature experiment melting point: 1350 C size distribution volume distribution March size (Å) ,

8 Q y s-phase in SC16 Ni-base single-crystal superalloy Large volume fraction of large g' precipitates => wide streaks along <100> directions Additional narrow streaks in certain directions (<111>, <320>) => large (thickness > 0.4 mm) precipitates of s- phase (topologically close packed - TCP) SANS E2 3.5E3 2.2E E E4 3.53E E E [111] CMSX3 creep exposition 900 C/300MPa/43h =0 TEM image of s-plate in SCA superalloy Q gray scale: measured data contour lines: fitted data 8

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10 In-situ SANS Study of Pore Microstructure in ZrO 2 Thermal Barrier Coatings cooperation with prof.vassen, DLR Juelich 10

11 Thermal barrier coatings - plasma sprayed ceramics hot gas ZrO 2 TBC superalloy T ( C) Porous ceramic layers covering elements exposed to high temperatures and corrosive environment Higher temperature => efficiency Preparation: Air Plasma Spraying (APS), Electron Beam Physical Vapor Deposition (EB PVD) highly porous material, pore microstructure determines properties 11

12 d /d (cm -1 sr -1 ) creation of nanopores from ex-situ: there are nanopores after 1h at 1200 ºC => created between 400 and 1200ºC cross section 68 C 410 C 812 C 813 C, 1 hour 1192 C 1200 C, 1 hour set 47 sample 2F Q (nm -1 ) nanopores created at 800ºC 12

13 volume fraction (dimensionless) mean radius (nm) Temperature ( C) Thermal barrier coatings YSZ in-situ SANS nanopores ºC: nanopores created from oxygen vacancies annealing at 1200ºC: sintering ex-situ volume fraction Temperature nanopores mean radius in-situ ex-situ :00 04:00 08:00 12:00 24:00 100:00 similarity in the time scale of pore sintering and of Young s modulus increase => the sintering of intra-splat pores have a role in the stiffening 800 C time (hours) B B A A

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15 Investigation of metalmatrix composite containing liquidphase dispersion P. Strunz 1, D. Mukherji 2, R Gilles 3, T Geue 4, J. Rösler 2 1 Nuclear Physics Institute Řež near Prague, Czech Republic 2 TU Braunschweig, Institut für Werkstoffe, Braunschweig, Germany 3 TU München, Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Garching, Germany 4 Laboratory for Neutron Scattering, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland This research project has been supported by the European Commission under the Research Infrastructures Programme NMI3 15

16 Al-Pb system Al-Pb binary system: a model system Pb (fcc, a Pb = nm) - negligible solubility in Al (fcc, a Al = nm) no intermediate phases Strengthening soft particles facilitate relaxation of dislocation stress => attractive interaction particle - dislocation voids or liquid phase finely distributed in the solid matrix melting points of Al (T M-Al =660 C) and Pb (T M-Pb = C) very different => Pb as a liquid dispersion in solid Al matrix at T > T M-Pb 16

17 Experimental as-cast and ECAP samples Al-4wt.%Pb system High purity Al ( %) and Pb (99.8%), melting in vacuum arc furnace Pb particles coarse (up to µm scale), dispersed mainly at the grain boundaries ECAP, 8 passes refinement of the Pb particle dispersion: equal-channel angular pressing (ECAP) 17

18 Aim of the in-situ SANS experiment to confirm T M shift of the confined Pb particles eventually conclude on details of microstructure during thermal cycle around solid liquid transition 18

19 Q y Q y Q y Ex-situ measurements for different orientations ECAP Al-4%Pb 3.29E3-8.26E3 1.31E3-3.29E E n ECAP sample: anisotropy when ECAP neutron beam Pb: prolate ellipsoids Orientation Q x grey scale map: measured data, large: short axis 4800 Å long axis 8400 Å small: short axis 1500 Å long axis 2000 Å Orientation n Q x white equiintensity lines: fit Orientation n Q x 19

20 volume fraction times scattering contrast (a.u.) In-situ measurement, ECAP Al-4%Pb, thermal cycle RT C C - RT n 1 st thermal cycle: amount of small particles decr. amount of large particles incr volume fraction times scattering contrast Total intensity: step in the temperature dependence <= melting of Pb maps the solid-liquid transition ( 342 C) of confined Pb; 15K shift with respect to free change of scattering contrast in the vicinity of T M : transition region K ( C), i.e. 26K broader Pb size distribution (size dependent T M ) T M free Pb not sharp smaller particles larger particles sum of both Temperature (K) 20

21 Metallic and ceramic materials: What can be investigated? Structure and microstructure Phase transformations (e.g. martensitic in SMA) Phase content Residual stresses in depth Microstresses Precipitates in alloys, particle dispersions Precipitate formation/dissolution Nanoscaled materials, nanoparticles Porosity Interfaces and surfaces of catalysts, semipermeable membranes In-situ tests at operational conditions Non-destructive testing 24