1 Analysis of Glass-forming Alloy by Synchrotron Radiation T. A. Başer /NIS Università degli Studi di Torino/ITALY European School-BMGs/ 13-1 Sept /Torino-ITALY
Fe-based Bulk Metallic Glasses with Y Addition Addition of large atoms, such as Y, is very helpful in terms of glass formation Y played the role of oxygen scavenger in Fe-Cr-Mo-C-B alloys, which led to the suppression of heterogeneous nucleation and improved glass formability. Ponnambalam V. and Poon Joseph S., J. Mater, Vol19, No.5, 13 () Glass formation in Fe-based alloy with Y addition is favored thermodynamically, resulting in an evident enhancement of GFA. Y effectively shifts the alloy composition from off-eutectic close a eutectic points. Lui Z. P., Liu C. T., Thompson J. R. and Porter W. D., Phys. R. Lett vol.9 no, 553-1, () European School-BMGs/ 13-1 Sept /Torino-ITALY
3 8 1 1.7..5..3. Heat Flow.1. -.1 -. -.3 -. -.5 -. -.7 -.8 -.9-1. Fe 8 Cr 15 Mo 1.1 W /g Exothermic 1 Y C 15 B - as-cast sample Crystallisation Behaviour The crystallisation gives various overlapped exothermic peaks 1 C/min 5 7 8 9 1 Temperature ( C) 8 The crystallisation products likely constitute a metastable mixture, as evidenced by the small exothermic peak OR It is caused by some residual amorphous structure. There is some residual amorphous fraction after crystallisation European School-BMGs/ 13-1 Sept /Torino-ITALY
ESRF/id11 water circulator Pt thermocouple inside of the stage Sample holder-linkam hot stage up to 1 C European School-BMGs/ 13-1 Sept /Torino-ITALY
5 Crystallisation Behaviour of Fe sample WAXS Results T i :5 ºC T f :1 ºC Scanning rate: 1 ºC/min ESRF/ID11 Fe 8 Cr 15 Mo 1 λ=.159 A 1 Y C 15 B as-cast 1 1 1 8 Intensity 1 1 3 5 7 8 9 θ 7 Temperature ( C) Increased by 1ºC! European School-BMGs/ 13-1 Sept /Torino-ITALY
Crystallisation Behaviour of Fe sample Fe 8 Cr 15 Mo 1 1 1 1 Y C 15 B as-cast 1 1 1 ºC/min T x 1 st crystallisation T 1 Amorphous phase Intensity Fully amorphous 1 st nd Temperature (ºC) 7 8 9 Exothermic T nd crystallisation 1 3 5 7 8 9 θ 1 Small exothermic peak T x (ºC) T 1 (ºC) T (ºC) DSC 9 9 7 LINKAM 7 79 97 ΔT 111 11 8 European School-BMGs/ 13-1 Sept /Torino-ITALY
7 RIETVELD REFINEMENT Paracrystal Model By comparing partial radial distribution functions of metallic glasses with those of their crystalline counterparts, we attempt to give an answer to the question as to which similarities exist between the short range atomic order found in amorphous structures and that found in crystals. For this purpose the concept of paracrystallinity is used.the atomic size play a part only in geometrical scaling factors.crystal structures used in the calculations of RDFs for para-crystals. Behind the idea of para-crystal model that crystal size is reduced, grain is not needed anymore. Sietsma J. And Thijsse B.,J. Non-Cryst. Solids 11 (1988) 135-15. Rietveld Quantitative amorphous content analysis The method derives the amorphous content from the small over-estimation of an internal crystalline standart in a Rietveld Refinement of an appropriate mixture. This approach focused on crystal fractions. There is no explanation of amorphous fraction. There is no physical information about background. J. Appl. Cryst. 3, (1), 19-. European School-BMGs/ 13-1 Sept /Torino-ITALY
8 Intensity 8 1 7 1 5 3 1 Rietveld Refinement (by Maud) Fully Amorphous Sample 1 3 5 7 8 9 θ total experimental background paracrystal model silica glass 8 Fe 3 C is used as a paracrystalline The same calculation was performed, but this calculation was not in better agreement with the experimental data. Silica glass is used to eliminate the effect of quartz capilary European School-BMGs/ 13-1 Sept /Torino-ITALY
9 8 1 9 1 Intensity 3 After 1 st Crystallisation Event total experimental background paracrystal model Cr 3 C silica glass 8 8 Intensity After nd Crystallisation Event 8 1 1 total experimental background paracrystal Cr 3 C +Fe 3 Mo 3 C silica glass 8 - -3 1 3 5 7 8 9 θ - 1 3 5 7 8 9 θ Cr 3 C phase occured during 1 st crystallisation Fe 3 Mo 3 C phase occured during nd crystallisation Amorphous phase fraction:.81 Amorphous phase fraction:.13 European School-BMGs/ 13-1 Sept /Torino-ITALY
1 8 1 9 1 total 8 experimental background 7 Cr 3 C 8 Intensity 5 3 Rietveld Refinement (by Gsas) After 1 st Crystallisation Event 8 1 1 total 8 experimental background Cr 3 C and Fe 3 Mo 3 C 8 Intensity After nd Crystallisation Event 1 1 3 5 7 8 9 θ 1 3 5 7 8 9 θ Cr 3 C phase occured during 1 st crystallisation Fe 3 Mo 3 C phase occured during nd crystallisation European School-BMGs/ 13-1 Sept /Torino-ITALY
11 Comparison pattern of crystals using by maud and gsas 8 1 1 Intensity After 1 st Crystallisation Event maud gsas 8 Cell parameters Phase Quantity Crystal Size Micro Strain Cr 3 C a=1.773 A (maud) a=1.7 A (gsas).51 (maud) 11.38 A (maud).5 (maud) Cr 3 C phase has been identified by paracrystalline model 1 3 5 7 8 9 θ Cr 3 C phase has been identified without paracrystalline model European School-BMGs/ 13-1 Sept /Torino-ITALY
1 After nd Crystallisation Event 8 1 7 5 Intensity 3 1-1 - -3 1 3 5 7 8 9 θ maud gsas Cell parameters Phase Quantity Crystal Size Micro Strain Cr 3 C a=1.78 A (maud) a=1.753 A (gsas) Fe 3 Mo 3 C a=11.17 A (maud) a=11.171 A (gsas).315 (maud).1 (maud).73 A (maud) 8.777 A (maud).5 (maud).11 (maud) Cr 3 C and Fe 3 Mo 3 C phases have been identified by paracrystalline model Cr 3 C and Fe 3 Mo 3 phases have been identified without paracrystalline model European School-BMGs/ 13-1 Sept /Torino-ITALY
13 Small Peak T (ºC) DSC 975 WAXS ΔT 15 75.5 1 C/min Heat Flow. 8 1 1 Exotherm ic 7 8 9 1 Tem perature ( C) 8 It is caused by some residual amorphous structure. There is some residual amorphous fraction after nd crystallisation Fe.3 Cr 5 Co 5 Mo 1.8 Mn 11. C 15.8 B 5.9 (Fe.3 Cr 5 Co 5 Mo 1.8 Mn 11. C 15.8 B 5.9 ) 98.5 Y 1.5 Lui Z. P., Liu C. T., Thompson J. R. and Porter W. D., Phys. Rev. 9 (), 553-1. Ponnambalam V. and Poon Joseph S., J. Mater. Res, 19, (), 13. European School-BMGs/ 13-1 Sept /Torino-ITALY
1 Between 1 st and nd Crystallisation (by Gsas) lattice constant vs. temperature a, Cell Parameter (A ) 1.75 1.75 1.78 1.7 1.7 1.7 1.7 8 1 1 1 st crystallisation 1.738 78 8 8 8 8 88 9 9 9 9 98 Temperature ( C) nd crystallisation 8 Temperature( C) Cell Parameter (A ) 79 815 8 85 1.75 97 1.753 As temperature increase lattice constants increase OR 1.7 1.75 1.773 Change of composition. If an element in (Fe,Cr) or (C,B) changed, they might be change the lattice constant European School-BMGs/ 13-1 Sept /Torino-ITALY
15 Conclusions Paracrystal and Quantitative Models are both suitable with ESRF data These approaches are also suitable for composites The open problem is what is the phase to select for paracrystalline model? Small peak which was observed after crystallisation caused by some residual amorphous structure. There is some residual amorphous fraction after crystallisation European School-BMGs/ 13-1 Sept /Torino-ITALY
1 Cu 5 Zr 5 binary system and Cu 5 Zr 5 with Al or Nb additions!as the ratio of shear modulus μ to bulk modulus B increases or poison ratio ν decreases, the material becomes brittle A.L. Greer, Y. Zhang, submitted paper as part of the proceedings of ISMANAM, Paris, -7 July 5!Minor additions of Al increase the glass-forming ability: with addition of at. % Al to Cu 5 Zr 5 W.H. Wang, J. J. Lewondowski and A. L. Greer, J. Mater. Res., Vol, No9, Sep5. European School-BMGs/ 13-1 Sept /Torino-ITALY
17 Melting Behaviour of Cu T Cu 5 Zr 5 5 master alloy- WAXS Results ESRF/ID11 λ=.159 A 3 5 15 1 5 runs were performed t yirmibes yirmi onbes on bes 1 3 5 7 8 S (nm) -1 European School-BMGs/ 13-1 Sept /Torino-ITALY
18 Melting Behaviour of Cu Results Cu 8 Zr 8 Al Al master alloy- WAXS ESRF/ID11 λ=.159 A 3 5 15 1 5 1 3 5 7 8 S (nm) -1 European School-BMGs/ 13-1 Sept /Torino-ITALY
19 Melting Behaviour of Cu Results Cu 8 Zr 8 Nb ESRF/ID11 Nb master alloy- WAXS λ=.159 A 7 5 55 5 5 35 3 5 15 1 5-5 1 3 5 7 8 S (nm) -1 European School-BMGs/ 13-1 Sept /Torino-ITALY
Phase identification on selected pattern (CuZr master alloy) ( ) Cu 1 Zr 7 ( ) CuZr cubic 8 1 1 ( ) CuZr ( ) CuZr monoclinic basic (O) CuZr monoclinic super 8 Binary Phase Diagram of Cu-Zr Intensity During solidification During first melting First pattern 1 3 5 7 8 9 1 11 1 θ Cu Zr European School-BMGs/ 13-1 Sept /Torino-ITALY
Acknowledgements: A. Reza Yavari M. Stoica K. Hajlaoui J. Das M. Bostrom Thank you for your attention!