Some (other) Uses of Diffusion Couples in Metallurgy: Model Calibration and Mapping Transitions in Mechanisms

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1 Engineering Conferences International ECI Digital Archives Harnessing The Materials Genome: Accelerated Materials Development via Computational and Experimental Tools Proceedings Fall Some (other) Uses of Diffusion Couples in Metallurgy: Model Calibration and Mapping Transitions in Mechanisms Christopher Hutchinson Department of Materials Engineering, Monash University Follow this and additional works at: Part of the Biomedical Engineering and Bioengineering Commons Recommended Citation Christopher Hutchinson, "Some (other) Uses of Diffusion Couples in Metallurgy: Model Calibration and Mapping Transitions in Mechanisms" in "Harnessing The Materials Genome: Accelerated Materials Development via Computational and Experimental Tools", J.-C. Zhao, The Ohio State Univ.; M. Asta, Univ. of California Berkeley; Peter Gumbsch Institutsleiter Fraunhofer-Institut fuer Werkstoffmechanik IWM; B. Huang, Central South University Eds, ECI Symposium Series, (2013). materials_genome/15 This Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in Harnessing The Materials Genome: Accelerated Materials Development via Computational and Experimental Tools by an authorized administrator of ECI Digital Archives. For more information, please contact

2 Some (other) Uses of Diffusion Couples in Metallurgy: Model Calibration and Mapping Transitions in Mechanisms Christopher Hutchinson Department of Materials Engineering, Monash University, Melbourne, Australia Students/PD: Y. Chen, W. Sun, C. Qiu (Monash), M. Styles (CSIRO) Collaborators: A. Deschamps, F. de Geuser, Y. Brechet (INPG), M. Gibson, A. Hill, T. Bastow (CSIRO), C. Sinclair (UBC), H. Zurob, G. Purdy (McMaster) Acknowledgements: Australian Research Council, Industrial Contributions

3 Examples using diffusion couples Modelling recystallization and grain growth during TMP o Grain boundary mobility? Design of non- isothermal heat treatment proviles for precipitation hardening systems o Solid state nucleation? Model calibration Rapid Hardening in Al- Cu- Mg alloys Composition dependence Ferrite growth in Fe- C- X steels Composition/velocity dependence of interfacial conditions Mapping transitions

4 RXF and GG during TMP of Nb-Steels We must be able to describe the composition dependence of the grain boundary mobility Models exists (Turnbull 1951, Cahn 1962) Intrinsic Mobility Solute Drag M D = β b Gb Fe Pure 2 V m RT δ M ( X Nb, T) 1 = + α X Nb M Pure 1 α = N V E ( kt ) b D Int Nb 2 δ Eb sinh kt E b kt

5 A high(er)-throughput approach

6 Cold deformation of the diffusion couple

7 Recrystallization in a temperature gradient Gleeble Thermo-mechanical Simulator

8 Evolution of Grain Structure Experimental Results: 100sec Annealing We should be able to describe the shape of the RXF/No RXF boundary (T, X Nb ) and the α grain size as a function of T and X Nb C Sinclair, CR Hutchinson and Y Brechet, The Effect of Nb on Recrystallization and Grain Growth in Ultra-High Purity a-fe: A Combinatorial Approach Metall. Mater. Trans. A. 38A, pp , 2007.

9 Experiment and (RXF and GG) Model Experimental Results: 100sec Annealing C Sinclair, CR Hutchinson and Y Brechet, The Effect of Nb on Recrystallization and Grain Growth in Ultra-High Purity a-fe: A Combinatorial Approach Metall. Mater. Trans. A. 38A, pp , 2007.

10 Experiment and (RXF and GG) Model Grain size evolution C Sinclair, CR Hutchinson and Y Brechet, The Effect of Nb on Recrystallization and Grain Growth in Ultra-High Purity a-fe: A Combinatorial Approach Metall. Mater. Trans. A. 38A, pp , 2007.

11 Designing Non-isothermal HT profiles What efviciencies may be found through the use of tailored non- isothermal heat treatment proviles for precipitation hardenable systems?

12 Designing Non-isothermal HT profiles Model System Fe- 2Cu (wt. %) Precipitation of spherical pure Cu Coupled model for precipitation and strengthening dn dt Nucl Precipitation Model * = β ZN dr dt dr dt 0 Growth Coarse ΔG exp kt D = R = 4 27 α Cu D X * t 1 exp τ X ss α / ε Cu Cu α / ε 1 X Cu α Cu 2 R R 0 X 1 eq Cu eq X Cu 500 C 1000h E sin 1 E E sin 1 E Strengthening Model p m p m σ = C ss sol W Cu σ k gr = d µb E σ = P M 50 λ E µb E p σ = 1 50 p M λ Em p m

13 Designing Non-isothermal HT profiles What is the optimum T(t) profile? Let us choose (t f, T f ) to compare with peak hardnesses in isothermal treatments, i.e. (t f, T f )=(1800s, 550 o C) Isothermal: 550 o C, 1800sec σ=840mpa Best Path: (t f, T f )=(1800s, 550 o C) m~4, T i ~400 o C σ=890mpa

14 Designing Non-isothermal HT profiles What is the optimum T(t) profile? There exists a whole family of curves that are significantly better that isothermal CR Hutchinson, M Goune and A Redjaimia, Selecting Non-Isothermal Heat Treatment Schedules for Precipitation Hardening Systems: An Example of Coupled Process-Property Design Acta Materialia, 55, pp , 2007.

15 Designing Non-isothermal HT profiles There are lots of possibilities: energy savings, faster treatments, more robust treatments, higher strengths, different structures giving the same strength, coupled process- property design.etc. But, almost always, nucleation is a problem. We always need to tune our descriptions of nucleation CR Hutchinson, M Goune and A Redjaimia, Selecting Non-Isothermal Heat Treatment Schedules for Precipitation Hardening Systems: An Example of Coupled Process-Property Design Acta Materialia, 55, pp , 2007.

16 A high(er)-throughput approach to study precipitation (N, R, Fv) Using diffusion couples to study the composition dependence of the nucleation rate (with or without deformation (gradients)) In-situ SAXS (ESRF, AS) In-situ thermal treatment of diffusion couples in SAXS beam q X-ray beam (~200µm)

17 In-situ SAXS of precipitation In-situ thermal treatment of diffusion couples in SAXS beam Kratky Plot (t=t 1 ); Cu/Cu-2Co Diffusion couple is scanned back and forward in the beam as a function of time to monitor the composition dependence of the precipitation kinetics Extract Fv, R (N) (t, T, X) From N(t, T, X) try to describe nucleation M. Styles, A. Deschamps, F. de Geuser, M. Gibson, CR Hutchinson.

18 In-situ SAXS of precipitation Diffusion couples and sputtered and annealed samples are being used Provides flexibility in gradient size Looking at the effect of deformation (channel die compression of diffusion couples) Looking at constant composition samples with gradients of deformation (e.g. capillaries EDM ed from tensile samples with non-constant gauges)

19 Rapid Hardening in Al-Cu-Mg alloys Interesting effect in a certain composition range where a very large amount of hardening is observed in 2min, followed by not much change for many hrs We have used Al-Cu/Al-Cu-Mg and Al-Mg/Al-Cu-Mg diffusion couples to map the transitions in the RHP RWK Marceau, C Qiu, SP Ringer and CR Hutchinson, A Study of the Composition Dependence of the Rapid Hardening Phenomenon in Al-Cu-Mg alloys Using Diffusion Couples, MSEA, 546, , 2012.

20 Rapid Hardening in Al-Cu-Mg alloys Al-2.2Cu/ Al-2.2Cu-1.2Mg/ Al-1.2Mg Gradient in Mg Al-3Cu/ Al-3Cu-1.8Mg/ Al-1.8Mg Gradient in Cu

21 Rapid Hardening in Al-Cu-Mg alloys Adding Cu to Al-1.7Mg and Al-2.3Mg Transitions in behaviour Adding Mg to Al-2.2Cu and Al-3Cu

22 Ferrite Growth in Fe-C-Ni Steels Long time question regarding the chemical conditions at migrating ferrite interfaces in Fe-C-X steels and where the transition from unpartitioned to partitioned growth occurs Fe-1Ni/Fe-5Ni diffusion couple 10 8 isoactivity line for C in 6 5 (wt. %) Ni 6 4 PE Phase Boundary (wt. %) Ni LE-P/LE-NP Boundary (wt. %) C + rolling + carburization Position (µm) CR Hutchinson, A Fuchsmann, HS Zurob and Y Brechet, A Novel Experimental Approach to Identifying Kinetic Transitions in Solid State Phase Transformations, Scripta Materialia, 50, , 2004.

23 Ferrite Growth in Fe-C-Ni Steels Ferrite growth by precipitation Exactly LENP Ferrite growth by decarburization CR Hutchinson, A Fuchsmann, HS Zurob and Y Brechet, A Novel Experimental Approach to Identifying Kinetic Transitions in Solid State Phase Transformations, Scripta Materialia, 50, , A Phillion, HS Zurob, CR Hutchinson, H Gao, DV Malakhov, J Nakano, and GR Purdy., Studies of the Influence of Alloying Elements on the Growth of Ferrite from Austenite under Decarburisation Conditions: Fe-C-Ni, Metall. Mater. Trans. A., 35A, pp , 2004.

24 Conclusions Samples containing gradients (composition, deformation, temperature, etc.) can be useful tools to: Calibrate and check models entering into larger through-process models To help identify transitions in behaviour and the limits of applicability of our simple (one or two mechanism) models in metallurgy