Presentation is loading. Please wait.

Presentation is loading. Please wait.

Sous la direction de : Jean-Jacques Blandin

Similar presentations


Presentation on theme: "Sous la direction de : Jean-Jacques Blandin"— Presentation transcript:

1 Sous la direction de : Jean-Jacques Blandin
26/03/2017 Comportement mécanique des verres métalliques massifs - Effet d’une cristallisation partielle Sébastien Gravier Sous la direction de : Jean-Jacques Blandin

2 Supervised by : Jean-Jacques Blandin
26/03/2017 Mechanical behavior of bulk metallic glasses - Impact of the partial crystallization Sébastien Gravier Dire qu’on va commencer par faire un rappel !!! Supervised by : Jean-Jacques Blandin

3 Conventional solidification
26/03/2017 Cooling a metal  Crystallization Volume Tm Temperature Notion de verre métallique massif pourquoi veut-on fabriquer des verres métalliques ?? Solid state Liquid state

4 Production of a metallic glass
26/03/2017 Cooling a metal  Crystallization Tg Glassy state Metallic glass To avoid crystallization  Rapid cooling Volume Limited size ! Tm Temperature More complex compositions to have Bulk metallic glasses Notion de verre métallique massif pourquoi veut-on fabriquer des verres métalliques ?? Supercooled Liquid Region (SLR) Liquid state

5 Effects ? Aim of the work Crystallization Glassy state Supercooled
26/03/2017 Glassy state Supercooled Liquid Region Tg Room temperature : RT (T << Tg) High temperature : HT (T>Tg) Tg Crystallization Volume Temperature Nanocrystals 100 nm brittleness large strain 5 mm Faire attention sur le fait que on peut déformer à haute température sans cristalliser !! Rajouter à l’oral que les verres c’est vachement intéressant car on a des bonnes propriétés à ambiante et grande capa de mise en forme Souligner l’intérêt de regarder la cristallisation : on peut la subir (gêner la mise en forme) et/ou la provoquer (fabrication de nanocomposites) Les effets semblent intéressant mais ont été très peu étudiés Effects ?

6 Validation for the amorphous alloy
Aim: effect of crystallisation on mechanical properties at RT and HT Room Temperature High Temperature Validation for the amorphous alloy Mechanical characterisation methods compression compression nanoindentation DMA How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

7 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy Microstructural characterisation DSC TEM XRD Crystal volume fraction ? How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

8 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy DSC XRD TEM Microstructural characterisation Crystal volume fraction ? How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

9 BMG studied in this thesis
Room temperature 26/03/2017 BMG studied in this thesis Vit1 (Tg = 365 °C ) Elements Zr Ti Cu Ni Be Atomic % L’état amorphe a été vérifié par XRD et MET

10 Vit1 (Tg = 365 °C ) Macroscopic brittleness but local plasticity
Room temperature 26/03/2017 BMG studied in this thesis Vit1 (Tg = 365 °C ) Elements Zr Ti Cu Ni Be Atomic % E ≈ corresponding crystalline alloys + sf = 1830 MPa ( 1 %)  eelast ≈ 0.02 Macroscopic brittleness Microscopic plasticity Fracture surface E f E même ordre de grandeur qu’un alliage de Zr Préciser déformation élastique environ 10 fois supérieure à alliages conventionnels !! elast Compression tests at room temperature on a BMG Macroscopic brittleness but local plasticity

11 L h Room temperature Loading curve : Unloading curve: L = C h2
26/03/2017 Loading curve : L = C h2 Unloading curve: ( Irreversible Work ratio ) RW = Wirr / Wtot L h Des essais de nanoindentation on t été effectués en collaboration avec ludovic charleux On représente ici la courbe de charge / décharge d’unb essai d’indentation : On peut extraire globalement 2 paramètres de cet essai; un lié à la charge et un lié à la décharge. La charge peut être modélisée par une parabole étant donné que les effets de tailles sont faibles ce qui permet d’obtenir C… Il est surprenant que le rapport des travaux soit aussi haut… signe de plasticité importante Nanoindentation loading and unloading curves Collaboration: L. Charleux ( INP-Grenoble )

12 Suggest many dissipative events !
Room temperature 26/03/2017 Loading curve : L = C h2 Unloading curve: ( Irreversible Work ratio ) RW = Wirr / Wtot Wtot Wirr = 67 % > Silica Glass ≈ 40 % < Aluminium ≈ 100 % Suggest many dissipative events ! Des essais de nanoindentation on t été effectués en collaboration avec ludovic charleux On représente ici la courbe de charge / décharge d’unb essai d’indentation : On peut extraire globalement 2 paramètres de cet essai; un lié à la charge et un lié à la décharge. La charge peut être modélisée par une parabole étant donné que les effets de tailles sont faibles ce qui permet d’obtenir C… Il est surprenant que le rapport des travaux soit aussi haut… signe de plasticité importante Nanoindentation loading and unloading curves

13 Suggest many dissipative events !
Room temperature 26/03/2017 Loading curve : L = C h2 Unloading curve: ( Irreversible Work ratio ) RW = Wirr / Wtot Sd Wtot Wirr = 67 % > Silica Glass ≈ 40 % < Aluminium ≈ 100 % Suggest many dissipative events ! AFM measurements : reduced Young modulus : Eeq La connaissance de la raideur de décharge Sd et une mesure de l’aire de contact par AFM nous permet de rajouter à ces deux valeurs celle du module d’Young réduit. Ces mesures ont un grand intérêt car on a pu montrer…. Nanoindentation loading and unloading curves Materials Science and Engineering A (2006)

14 Von Mises criterion : sy  Line in this plane
Room temperature 26/03/2017 In this plane Von Mises criterion : sy  Line in this plane Plasticity map extracted from nanoindentation curves: gives plastic properties independently of elastic behavior

15 Von Mises criterion : sy  Line in this plane
Room temperature 26/03/2017 In this plane Von Mises criterion : sy  Line in this plane  > 0  < 0 Drucker Pragger criterion : sy and α (pressure sensitivity) Upper part :  > 0 Lower part :  < 0 Plasticity map extracted from nanoindentation curves: gives plastic properties independently of elastic behavior

16 Von Mises criterion : sy  Line in this plane
Room temperature 26/03/2017 In this plane Von Mises criterion : sy  Line in this plane  > 0  < 0 Drucker Pragger criterion : sy and α (pressure sensitivity) Upper part :  > 0 Lower part :  < 0  Both values of sy in agreement with compression  in agreement with Vaidyanathan 2001 Patnaik 2004 Plasticity map extracted from nanoindentation curves: gives plastic properties independently of elastic behavior Nanoindentation: Fruitful technique to study deformation at room temperature (in particular pressure sensitivity)

17 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy DSC XRD TEM Microstructural characterisation Crystal volume fraction ? How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

18 High temperature Large strains Viscoplastic deformation in
26/03/2017 Compression tests at Tg + 10 °C, various strain rates Large strains Viscoplastic deformation in steady state Viscosity as function of strain rate / compression

19 Confirmation of usual deformation behaviour in SLR
High temperature 26/03/2017 Confirmation of usual deformation behaviour in SLR Newtonian regime High temperature / low strain rate Non Newtonian regime Low temperature / high strain rate Non Newtonian Newtonian Citer Marc Bletry à l’oral Viscosity as function of strain rate / compression

20 effect of T : just translation
High temperature 26/03/2017 Ability to draw a master curve: Sensibility of viscosity to strain rate independent of temperature effect of T : just translation Sensitivity to temperature: Newtonian viscosity Importance de la viscosité Newtonienne qui permet, si on la connaît à la température considérée, de connaître les viscosités d’écoulement à en fonction de la vitesses de déformation. On peut d’ailleurs extrapoler relativement bien cette viscosité en modélisant sa dépendance à la température par un loi de type Arhénius. On trouve alors une énergie d’activation élevée de 440kJ/mol. Cette énergie suggère que le mécanisme de déformation est complexe et comprend plusieurs atomes… Creation of a unique master curve for various temperatures Suppose: Q = 440 kJ/mol Complex multiatomic mechanism (activation volume ≈ 20 atoms) in large strain … (strong temperature sensitivity)

21 Data obtained in steady state (large strain)
High temperature 26/03/2017 Ability to draw a master curve: Sensibility of viscosity to strain rate independent of temperature effect of T : just translation Sensitivity to temperature: Newtonian viscosity Importance de la viscosité Newtonienne qui permet, si on la connaît à la température considérée, de connaître les viscosités d’écoulement à en fonction de la vitesses de déformation. On peut d’ailleurs extrapoler relativement bien cette viscosité en modélisant sa dépendance à la température par un loi de type Arhénius. On trouve alors une énergie d’activation élevée de 440kJ/mol. Cette énergie suggère que le mécanisme de déformation est complexe et comprend plusieurs atomes… Creation of a unique master curve for various temperatures Data obtained in steady state (large strain) Is there a minimum strain to measure these features ? Suppose: Q = 440 kJ/mol Complex multiatomic mechanism (activation volume ≈ 20 atoms) in large strain …

22 Phase difference between applied stress and strain
High temperature 26/03/2017 Dynamic Mechanical Analysis (DMA) : Sinusoidal small strain tests Phase difference between applied stress and strain Dissipative part of the deformation : Frequency scans at various fixed temperatures T Spectromécanique en collaboration avec Jean-Marc Pelletier. Permet d’appliquer des déformation très faibles et inférieures à !! Construction of a master curve Collaboration: Jean–Marc Pelletier, INSA - Lyon

23 High temperature 26/03/2017 Dynamic Mechanical Analysis (DMA) : Sinusoidal small strain tests Phase difference between applied stress and strain Dissipative part of the deformation : T Elementary mechanism of deformation independent of T Apparent activation energy ~ kJ/mol  Similar mechanical behaviours in the investigated conditions (T and both small and large strains) Spectromécanique en collaboration avec Jean-Marc Pelletier. Permet d’appliquer des déformation très faibles et inférieures à !! DMA + Compression : Fruitful techniques to study deformation at HT in a large strain interval Frequency scans at various fixed temperatures Construction of a master curve Collaboration: Jean–Marc Pelletier GEMPPM, INSA

24 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy Microstructural characterisation DSC TEM XRD Crystal volume fraction ? How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

25 Crystallization / Microstructure
26/03/2017 Amorphous : transformed fraction Ft = 0% Isothermal annealing DSC at Tg + 50 °C Various heat treatments Crystallite average size Φ ~ 35 nm Ft ≈ 100 % 60 min. ~ 30 nm Ft = 10 % 10 min. Φ ~ 35 nm Ft = 80 % 45 min. Φ ~ 30 nm Ft = 45 % 20 min. Φ ~ 35 nm Ft = 60 % 30 min. Mentionner qu’il y a deux pics de cristallisation

26 Crystallization / Microstructure
26/03/2017 Amorphous : transformed fraction Ft = 0% Isothermal annealing DSC at Tg + 50 °C Various heat treatments Crystallite average size Φ ~ 35 nm Ft ≈ 100 % 60 min. ~ 30 nm Ft = 10 % 10 min. Φ ~ 35 nm Ft = 80 % 45 min. Φ ~ 30 nm Ft = 45 % 20 min. Φ ~ 35 nm Ft = 60 % 30 min. Spherical crystallites + constant average size

27 Crystallization / volume fraction
26/03/2017 Direct measurements through TEM imaging Crystal superposition and lack of contrast in bright field Bright field observation Dark field measurements of volume fraction Dark field observation Thickness measurement Collaboration: P. Donnadieu (LTPCM – INPG)

28 Crystallization / volume fraction
26/03/2017 Direct measurements through TEM imaging Crystal superposition and lack of contrast in bright field Bright field observation Dark field measurements of volume fraction Dark field observation Thickness measurement To calculate the real volume fraction we need to have only one crystal type : Crystallite size Crystallite nature 0 min. 10 min. 20 min. 30 min. Fv (%) 4  1 17  4 26  5 TEM volume fraction of crystals depending on annealing time at Tg + 50 °C  annealing time ≤ 30 min. Collaboration: P. Donnadieu (LTPCM – INPG)

29 Crystallization / volume fraction
26/03/2017 Direct measurements through XRD analysis Crystals randomly oriented Density constant (Dd / d < 1 %) Citer Patricia XRD curves for the various samples

30 Crystallization / volume fraction
26/03/2017 Direct measurements through XRD analysis Crystals randomly oriented Density constant (Dd / d < 1 %) Crystallized part 60 min. Amorphous part Amorphous Volume fraction of crystals Separation of the amorphous and crystalline contributions.

31 Crystallization / volume fraction
26/03/2017 Validation of the method Amorphous 10 min. 20 min. 30 min. Volume fraction (%) TEM 4  1 17  4 26  5 XRD 7  3 17  3 27  3 Equivalent values with the two methods :  Validation of the measurement methods XRD analysis is an accurate way to measure Volume fraction of crystals (even for small crystallites) Penser à la transition !!

32 Crystallization / volume fraction
26/03/2017 Validation of the method Amorphous 10 min. 20 min. 30 min. 45 min. 60 min. Volume fraction (%) TEM 4  1 17  4 26  5 ? XRD 7  3 17  3 27  3 32  3 45  5 Equivalent values with the two methods :  Validation of the measurement methods XRD analysis is an accurate way to measure Volume fraction of crystals (even for small crystallites) Penser à la transition !!

33 Crystallization / volume fraction
26/03/2017 Validation of the method Amorphous 10 min. 20 min. 30 min. 45 min. 60 min. Volume fraction (%) TEM 4  1 17  4 26  5 ? XRD 7  3 17  3 27  3 32  3 45  5 DSC Ft (%) 10 45 60 80 100 Equivalent values with the two methods :  Validation of the measurement methods XRD analysis is an accurate way to measure Volume fraction of crystals (even for small crystallites) Penser à la transition !! Large difference with predicted DSC transformed fraction (while sometimes used as crystalline fraction…)

34 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy DSC XRD TEM Microstructural characterisation Crystal volume fraction : OK How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

35 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy DSC XRD TEM Microstructural characterisation Crystal volume fraction : OK How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

36 Effect of crystallization / room temperature
26/03/2017 Fracture stress increases slightly and then falls ! Change in fracture mechanism : Fragmentation rather than shear fracture for Fv > 30 % Le matériau se fragmente !! Suggère une forte diminution de l’énergie de fracture Fracture stress as a function of annealing time Nanoindentation is even more interesting to study plasticity Journal of Alloys and Compounds (2006)

37 Effect of crystallization / room temperature
26/03/2017 Al Amorphous Silica Direqu’on a dézoomé Plasticity map extracted from nanoindentation curves Journal of Materials Research (2007)

38 Effect of crystallization / room temperature
26/03/2017 Al Effect of crystallization (Fv < 0.5) Very limited variations of Rw and C/Eeq Still sensitive to pressure Silica Plasticity map extracted from nanoindentation curves At room temperature: Effect on fracture rather than on deformation mechanisms Journal of Materials Research (2007)

39 Aim: effect of crystallisation on mechanical properties at RT and HT
Room Temperature High Temperature compression compression Mechanical characterisation methods nanoindentation DMA Validation for the amorphous alloy DSC XRD TEM Microstructural characterisation Crystal volume fraction : OK How the crystallisation modify the plasticity characteristics ? How the crystals contribute to change the mechanical response ? (rheology, elementary mechanism of deformation, reinforcement...)

40 Effect of crystallization / high temperature
26/03/2017 Deformation ability is maintained up to large Fv Two main effects of crystallization Increase of viscosity Promotion of non Newtonian behaviour Rappeler que la courbe de viscosité précédente donnait la dépendance de la viscosité pour différentes températures Dire que l’on peut toujours obtenir des taux de déformation supérieurs à 1 Viscosity depending on strain rate The reinforcement for a given temperature depends on strain rate

41 Effect of crystallization / high temperature
26/03/2017 Still ability to draw master curves Strain rate dependence of viscosity is the same for the various temperatures and Fv ~ 25 compression tests Effect of T : still just translation axis ou axes ?? Viscosity curves : all temperatures and annealing times / translated along the two axes Similar mechanical behaviours in the investigated conditions (Fv, T and large strains)

42 Effect of crystallization / high temperature
26/03/2017 ~ 200 curves Again able to draw master curves Same elementary mechanism of deformation for the various temperatures and Fv DMA curves : all temperatures and annealing times / translated along the two axis THERMEC (2006)

43 Effect of crystallization / high temperature
26/03/2017 Similar mechanical behaviours in the investigated conditions (Fv, T and both small and large strains) Prediction of the reinforcement factor ( ) ? The amorphous matrix seems responsible for the deformation Reinforcement depends on strain rate… Comparison performed in Newtonian regime La prédiction du comportement ne peut pas se faire par DSC qui ne donne pas la fraction volumique de cristaux!! Remarque JJB: les mécanismes de déformation sont similaires entre les différents partiellement cristallisé mais également entre les partiellement cristallisés entre eux

44 Effect of crystallization / high temperature / reinforcement
26/03/2017 T = Tg + 30 °C Prediction of R from mechanical models ? Hard sphere dispersion in a viscous media : Krieger model Krieger : on a des cristaux sphériques et préciser que c un modèle classique pour modéliser les dispersions Reinforcement factor for various Fv (less than 30 %)

45 Effect of crystallization / high temperature / reinforcement
26/03/2017 T = Tg + 30 °C Prediction of R from mechanical models ? Hard sphere dispersion in a viscous media : Krieger model Krieger model Underestimate the reinforcement !! Cependant, l’effet de la température n’est pas complêtement modifiée …. Reinforcement factor for various Fv (less than 30 %)

46 Effect of crystallization / high temperature / reinforcement
26/03/2017 Various T Prediction of R from mechanical models ? Hard sphere dispersion in a viscous media : Krieger model T decreases Tg Tg + 30°C Krieger model Underestimate the reinforcement !! Cependant, l’effet de la température n’est pas complêtement modifiée …. Reinforcement factor for various Fv (less than 30 %) and temperatures Reinforcement depends on strain rate and temperature (simple mechanical models are not adapted)

47 Effect of crystallization / high temperature / reinforcement
26/03/2017 Still able to use an Arrhenius law Activation energies in SLR measured by two ways Temperature Newtonian viscosity Glass Partially crystallized ISMANAM (2006)

48 Effect of crystallization / high temperature / reinforcement
26/03/2017 Still able to use an Arrhenius law Partially crystallized Newtonian viscosity Glass Dire que avec la DMA on va plus loin en Fv + souligner le bon accord !! Activation energies in SLR measured by two ways Temperature Reinforcement increases with temperature because: Decrease of viscosity is less rapid when crystals are present ISMANAM (2006)

49 Effect of crystallization / high temperature / activation energies
26/03/2017 Three possible reasons to explain the decrease of activation energy Direct change in composition of the residual glass ? NO ( ∆ Tg < 4 °C ) Direct contribution of crystal deformation ? NO ( TEM observations after deformation > 1.5 ) Dire qu’il n’y a pas de percolation. En dehors de mécanismes de percolation… ISMANAM (2006)

50 Effect of crystallization / high temperature / activation energies
26/03/2017 Three possible reasons to explain the decrease of activation energy Direct change in composition of the residual glass ? Direct contribution of crystal deformation ? Influence of the coupling between matrix and crystals ? d Dire que cela aura un impact important à cause des tailles nanométriques !! Matrix layer perturbed by the proximity of crystals Small “flow channels” between crystallites Modification of matrix activation energy at crystal neighborhood

51 Effect of crystallization / high temperature / activation energies
26/03/2017 coupling between matrix and crystals (crystal size ≈ 30 nm) ? 1 nm 3 nm 5 nm Fraction of amorphous matrix perturbed because of proximity of crystals Effect of various interface thickness Approche ressemblant à ce qui est utilisé dans les polymères

52 Effect of crystallization / high temperature / activation energies
26/03/2017 coupling between matrix and crystals (crystal size = 30 nm) ? Effect of various interface thickness Distance between crystallites effect Visualization of the small distances between crystals : Fv = 30 % 30 nm 5 nm 3 nm 1 nm For 30 % of crystals : more than half of the remaining amorphous matrix is perturbated by crystals while at the same time the activation energy is divided by 2 Bien que le lien direct entre cet affet de proximité et la baisse de la sensibilité à la température n’est pas encore établi !!! Fraction of amorphous matrix perturbed because of proximity of crystals Nanometer crystallites  Large fraction of the remaining amorphous matrix can be disturbed by crystal proximity

53 Main conclusions Validation of new methods - compression / nanoindentation  fracture vs. plasticity  calculation of both the pressure sensitivity and the yield stress - compression / DMA  large strain interval  deformation mechanism at small strains vs. large strain mechanism - TEM / XRD  Measurements of the volume fraction of crystals

54 Main conclusions Open questions on the effect of crystallization - At room temperature: Does the crystals modify the plasticity characteristics ?  Modify the fracture (fragmentation for Fv > 30 %)  Limited modification of the plastic mechanism Small variation of Rw Still a pressure sensitivity - At high temperature: How the crystals contribute to change the mechanical response ?  Deformation mechanism seems similar whatever Fv (< 50 %), the strain or the temperature  Promotion of non Newtonian behavior  Reinforcement effect depends on temperature

55 Perspectives / scientific
26/03/2017 Modelling the high temperature deformation Similarity between deformation mechanisms for small strain and large strain Interest of the definition of the elementary mechanism of deformation Il y a également différentes pistes qu’il nous semble intéressant de creuser dans l’avenir et je vais vous présenter ici 3 axes de recherche qui me semble intéressants pour l’avenir. On a tout d’abord mis en avant qu’il existait un effet lié à la taille des crystallites dans les mécanismes de déformation et il serait intéressant de créer des microstructures en faisant varier les tailles de cristaux. On a déjà obtenu un point de comparaison avec fractions volumiques similaires et tailles de cristaux différentes.

56 Perspectives / scientific
26/03/2017 Modelling the high temperature deformation Similarity between deformation mechanisms for small strain and large strain Interest of the definition of the elementary mechanism of deformation  Elementary shear mechanism of Argon Flow defect  Need to go from elementary deformation to macroscopic deformation Flow defect concentration Il y a également différentes pistes qu’il nous semble intéressant de creuser dans l’avenir et je vais vous présenter ici 3 axes de recherche qui me semble intéressants pour l’avenir. On a tout d’abord mis en avant qu’il existait un effet lié à la taille des crystallites dans les mécanismes de déformation et il serait intéressant de créer des microstructures en faisant varier les tailles de cristaux. On a déjà obtenu un point de comparaison avec fractions volumiques similaires et tailles de cristaux différentes.

57 Perspectives / scientific
26/03/2017 Study of the size effect of nanocrystals One comparison point already achieved: Fv = 16% + Mean crystallite size = 7 nm Fv = 17% + Mean crystallite size = 30 nm and No differences observed … … up to now !! Il y a également différentes pistes qu’il nous semble intéressant de creuser dans l’avenir et je vais vous présenter ici 3 axes de recherche qui me semble intéressants pour l’avenir. On a tout d’abord mis en avant qu’il existait un effet lié à la taille des crystallites dans les mécanismes de déformation et il serait intéressant de créer des microstructures en faisant varier les tailles de cristaux. On a déjà obtenu un point de comparaison avec fractions volumiques similaires et tailles de cristaux différentes.

58 Perspectives / technological
26/03/2017 Interest of bulk metallic glasses / metallic alloys composites Co-deformed multimaterials designed thanks to the deformation ability of the glass in the SLR  Resistance of metallic glass + ductility of metallic alloy 10 mm Push out tests 1 mm Al-alloy Vit1 1 mm Al-alloy Vit1 Interesting mechanical properties… Fracture stress + Plasticity + High interface shear stress Patent in progress Advanced Engineering Materials (2006)

59 Merci à … Ludovic Charleux Béatrice Doisneau-Cottignies Patricia Donnadieu Marc Fivel Alexandre Mussi Jean-Marc Pelletier Luc Salvo Jean-Louis Soubeyroux Michel Suery André Sulpice Marc Verdier Qing Wang … pour leurs contributions à ce travail 26/03/2017

60 26/03/2017

61 26/03/2017

62 Conclusion and ….perspectives
26/03/2017 Point not aborded Crystallites size effect (heat treatments at other temperatures) Room temperature Young modulus High temperature Model of deformation based on the Argon model Effect of the high temperature deformation on the crystallization Materials Science and Engineering A (2006)

63 Perspectives / scientific
26/03/2017 Link between localized deformation and homogeneous flow ? Compression test at room temperature: Zr based BMG with plasticity (collaboration with Shanghai university) eplastic > 0.07 Characterization of the localized deformation  Influence of a temperature increase  Transition with homogeneous flow On pourrait l’étudier sur du vit1 mais semble plus intéressant avec du ZrNb

64 Poisson ratio … deformation mechanism
26/03/2017 Pd Lewandowski et al., Phil. Mag. 2005 Yoshida et al., JMR 2005

65 Crystallisation 26/03/2017 Three crystallization events may occur at higher temperature… Analyze here the two first crystallization peaks Tp1 = 438 °C Tp2 = 457 °C Tp3 = 505 °C Tg ≈ 365 °C Isothermal Annealing at 410°C DSC scan at 10°/min. / amorphous sample

66 DMA / Activation energy
26/03/2017 DMA / Temperature scan Maxwell model and Activation energy: T<Tg : Q ≈ 100 kJ/mol Activation energy: T > Tg : Q ≈ 450 kJ/mol Calculation of the activation energy in Small deformation

67 Effect of crystallization : Newtonian Viscosity
26/03/2017 Fv = 32 % Influence of the temperature on the reinforcement Amorphous Activation energies in SLR measured by two ways ISMANAM (2006)

68 Effect of the deformation on the crystallization
26/03/2017 Reinforcement factor as a function of time. Cristallisation proceed while deforming No visible influence of the deformation on the crystallization Materials Science and Engineering A (2006)

69 Effect of the deformation on the crystallization
26/03/2017 DRX on two samples DSC on four samples No visible influence of the deformation on the crystallization Materials Science and Engineering A (2006)

70 Effect of the deformation on the crystallization
26/03/2017 Deformed No visible influence of the deformation on the crystallization Materials Science and Engineering A (2006)

71 High temperature Mechanism
26/03/2017 Multiatomic approach of the high temperature deformation Multiatomic deformation mechanism High apparent activation energy  Shear model of Argon  Resistance of the surrounding Qapparent = Q (interfacial shear resistance) + Q (mechanical resistance of the surrounding)

72 High temperature Mechanism
26/03/2017 Evolution of the activation energy Glassy state Supercooled liquid Liquid state Eact T > Tg Mechanical resistance of the surrounding is decreasing Eact: T < Tg Continuous decrease ? Eact T > Tf Tg Tf

73 High temperature Mechanism
26/03/2017 Defect concentration evolution DHf = 14 kJ /mol DSf = 6 J /mol/°C

74 Co-extruded materials
26/03/2017

75 Co-extruded materials
26/03/2017

76 Co-extruded materials
26/03/2017

77 Co-extruded materials
26/03/2017

78 Co-extruded materials
26/03/2017


Download ppt "Sous la direction de : Jean-Jacques Blandin"

Similar presentations


Ads by Google