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Innovative approach to structure control in light alloys

Innovative approach to structure control in light alloys. Dmitry Eskin, Hari-Babu Nadendla Brunel Centre for Advanced Solidification Technology. BCAST: Vision.

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Innovative approach to structure control in light alloys

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  1. Innovative approach to structure control in light alloys Dmitry Eskin, Hari-Babu Nadendla Brunel Centre for Advanced Solidification Technology

  2. BCAST: Vision • BCAST is an international leader in liquid metal engineering with focus on solidification research, strategic technology developments and user-led industrial applications. We conduct fundamental research to generate world-class knowledge in solidification science. We develop and exploit innovative and sustainable technologies and enable the metal casting industry and its customers to improve their competitiveness in global markets. Brunel University 8 constituent academic schools10 research institutes15,200 full-time students 2,500 staff BCAST 3 Professors 5 Lecturers 11 Research Fellows 8 PhD students 5 Support staff

  3. Research • Fundamental research: Nucleation–based solidification research including the structure of liquid metal, mechanisms of heterogeneous nucleation and the generic approach for enhancing and controlling nucleation through both physical and chemical methods. • Technology development: Innovative generic technologies for liquid metal treatment and applications of developed to the existing shape casting and continuous casting processes. • Industrial applications: Proprietary applied research with individual industrial partners to exploit fundamental research and generic technological development to support the metal casting industry in implementing innovative processing technologies and new products.

  4. Outline • Why we think that metals are underestimated in European programmes • Scandium – ultimate addition to Al alloys • Grain refinement using designed master alloys • Ultrasonic cavitation processing – universal technology • Conclusions

  5. What is the age we are living now in? Middle age Renaissance Industrial age Electronic age Nano- age? Iron age 1300 BC-300 BC Bronze age 3300 BC-600 BC Stone age 2.5 mln BC-2000 BC

  6. What are the important materials?

  7. What can be called extreme processing conditions? Temperature: 700-800 °C for Al melting and casting Speed: cm/s Pressure: 1 atm Time-scale: minutes to hours Length-scale: cm to meters

  8. What can be called extreme processing conditions? Temperature: more than 5000 K Speed: faster than 1500 m/s Pressure: up to 10000 atm Time-scale: less than 100 µsec Length-scale: 5 to 500 µm “The conditions inside the collapsing bubbles are theoretically extreme enough to allow nuclear fusion to take place.” Nature 440, p.132 (9 March 2006)

  9. Potential of Scandium Al-Sc master alloy Al alloy billet

  10. Effects of Scandium • Sc is prone to supersaturation in (Al) • Al3Sc is the only one phase in Al-based systems: • Equilibrium L12 phase • Lattice parameters perfectlymatching Al – can be coherent • Precipitates at 200-300 °C • Primary: perfect grain refiner • Secondary: powerful, coherent, equilibrium hardenerSecondary: powerful, equilibrium, stable grain blocker L. Toropova et al.

  11. How to realize the potential of scandium in aluminium alloys • Scandium is expensive soa much cheaper master alloy produced directly from oxidesis an alternative • Scandium can be added in combination with other elements, e.g. Zr, with resulting 2-3 times lower addition level • Scandium is not a rare metal, it is scattered. Increased bulk demand would result in lower costs and price

  12. 0.384 nm 0.384 nm 0.405 nm 0.405 nm Al Al (face centred cubic) Designed grain refiners based on less-common transition elements Al-Si alloys are the base for most castings used in cars, aircrafts, pumps, engines etc • New grain refiner has • Higher melting temperature than Al • Good lattice matching (with Al and Al-Si matrix crystals) • Chemical stability with Al and other commonly used alloying elements • No compounds with alloying elements (no poisoning)

  13. Al-Si alloy Al-Ti-B 2500 novel grain refiner 2000 m ] m [ 1500 Grain size 1000 500 -1 0 1 2 3 4 5 6 7 8 9 10 Si [ wt.% ] Al-Si binary alloys Tp1 test 700 OC Practical alloys composition Patent application M. Nowak & N. HariBabu

  14. Slow cooling rate 0.07 K/s LM6 LM6 with Grain refiner addition Without addition With NGR addition 20 mm M. Nowak & N. HariBabu

  15. Cavitation Cavitation zone (N. Alba-Baena et al., 2011) Acoustic streaming Non affected area (Garcia-Rodriguez et al , 2011) (D. Eskin et al., 2010)

  16. Cavitation

  17. Structure refinement in light alloys Al2O3 wetting • In the liquid state: activation of nonmetallic inclusions • In the liquid state: dispersion and refinement of nucleating substrates, e.g. intermetallics • In the solidification range: fragmentation of dendrites and dispersion of fragments • Primary intermetallics: fragmentation, nucleation Al3(Zr, Ti) D. Eskin et al.

  18. Degassing in Al (GA 286344) N. Alba Baena & D. Eskin, 2012

  19. Nanocomposite materials

  20. Nanocomposite materials

  21. Conclusions • The potential of advanced “conventional” metal is great and is related to less-common and scattered metals and to extreme processing. • Advances bring about economical, technical, societal and environmental impact. • There is large potential for fundamental scientific advances for support of advanced metallic materials.

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