The Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions-2 (MICAST-2) - 11.04.14
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The Microstructure Formation in Casting of Technical Alloys under Diffusive and Magnetically Controlled Convective Conditions-2 (MICAST-2) experiment aims to deepen the understanding of the physical principles that govern solidification processes in metal alloys. The patterns of the crystals resulting from transitions of liquids to solids is of substantial importance to processes in producing materials such as solar cells, thermoelectrics, and metal alloys.
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Alcan CRV, Voreppe, , France
HYDRO Al GmbH, , , Germany
Nemak Hungary, , , Hungary
Alcoa-Köfem Kft, , , Hungary
INOTAL, , , Hungary
Dunaferr Zrt., , , Hungary
Aleris, , , Netherlands
Sponsoring Space Agency
European Space Agency (ESA)
Earth Benefits, Scientific Discovery
ISS Expedition Duration
March 2011 - March 2015
Previous ISS Missions
MICAST-2 identifies and controls experimentally the fluid-flow patterns that affect microstructure evolution during casting processes, and to develop analytical and advanced numerical models. The microgravity environment of the International Space Station (ISS) is of special importance to this project because only there are all gravity-induced convections eliminated and well-defined conditions for solidification prevail that can be disturbed by artificial fluid flow being under full control of the experimenters. Design solutions that make it possible to improve casting processes and especially aluminum alloys with well-defined properties are provided.
MICAST-2 studies the influence of pure diffusive and convective conditions on aluminium-silicon (Al-Si) and aluminium-silicon-iron (Al-Si-Fe) cast alloys on the microstructure evolution during directional solidification with and without rotating magnetic field.
The specific goals of MICAST-2 are:
- To study the influence of controlled fluid flow on the primary and secondary dendrite arm spacing;
- Fluid Flow Effects on Intermetallic Phases in Aluminum-cast Alloys;
- Comparison with ground-based studies and previous sounding rocket experiments;
- To study the influence of controlled fluid flow on the segregation effects;
- To study the influence of different solidification velocities on the micro-structure evolution.
The MICAST experiments produce data that can improve computer models simulating metal solidification on Earth. Knowledge gained from the MICAST experiments could improve ground-based metal casting processes, leading to new stronger, lightweight materials.
The microgravity environment of the International Space Station is key for alloy research because gravity-induced actions are eliminated, and turbulence or convection can be carefully manipulated by the researchers. The experiments could improve ground-based development of new lightweight, high-performance materials that can be used in future space missions.
Each sample cartridge assembly (SCA) is fully processed in the Material Science Research Rack Materials Science Laboratory/Low Gradient Furnace (MSRR MSL/LGF), including final solidification step. After return to Earth, the SCA’s are destructively analyzed by the investigators. The structure of the solidified metallic alloy is then compared to predictions derived from complex numerical codes. This comparison helps to adapt and improve the numerical codes developed by scientists.
The crew member inserts one SCA into the MSRR MSL LGF. Following power on, the MSRR MSL/LGF and vary the power profile of the various furnace heaters to characterize the thermal behavior of the melted metallic alloy in the SCA. Temperature sensors signals are downlinked to Earth for in-depth assessment by science teams. Numerical codes provide additional information about the state of the SCA under the thermal constraints on orbit. For each SCA the conditions of the Rotating Magnetic Field (RMF) of the MSL are varied. Following cool down of the furnace, the SCA is removed from the MSL/LGF furnace, and stowed passively until return to Earth.
The samples for MSL MICAST-2 are as follows:
- MICAST1 SCA #1:Al-7wt% Si (four solidification velocities, free cooldown;
- MICAST1 SCA #2: Al-7wt% Si (constant Rotating Magnetic Field (RMF), four solidification velocities, free cooldown)
- MICAST1 SCA #3: Al-7wt% Si-1wt% Fe (four solidification velocities, free cooldown)
- MICAST1 SCA #4: Al-7wt% Si-1wt% Fe (constant RMF, four solidification velocities, free cooldown)
- MICAST1 SCA #5: Al-7wt% Si-1wt% Fe (four RMF settings, four solidification velocities, free cool down) MICAST
- SCA #6: Al-7wt% Si (oriented seed, two solidification velocities, TBD cool down)
- MICAST SCA #7: Al-7wt% Si (oriented seed, two solidification velocities, TBD cool down)
Zimmermann G, Schaberger-Zimmermann E, Steinbach S, Ratke L, Ratke L. Formation of intermetallic phases in AlSi7Fe1 alloy processed onboard the ISS. Materials Science Forum. 2014 May; 790-791: 40-45.
Budenkova O, Baltaretu F, Steinbach S, Ratke L, Ratke L, Roosz A, Roosz A, Ronafoldi A, Kovacs J, Bianchi A, Fautrelle Y. Modelling of Al-7%wtSi-1wt%Fe ternary alloy: Application to space experiments with a rotating magnetic field. Materials Science Forum. 2014 May; 790-791: 46-51. DOI: 10.4028/www.scientific.net/MSF.790-791.46.
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