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Influence of Laser Welding Speed on the Morphology and Phases Occurring in Spray-Compacted Hypereutectic Al-Si-Alloys

Gietzelt, Thomas; Wunsch, Torsten; Messerschmidt, Florian; Geßwein, Holger; Gerhards, Uta



Abstract (englisch): Normally, the weldability of aluminum alloys is ruled by the temperature range of solidification of an alloy according to its composition by the formation of hot cracks due to thermal shrinkage. However, for materials at nonequilibrium conditions, advantage can be taken by multiple phase formation, leading to an annihilation of temperature stress at the microscopic scale, preventing hot cracks even for alloys with extreme melting range. In this paper, several spray-compacted hypereutectic aluminum alloys were laser welded. Besides different silicon contents, additional alloying elements like copper, iron and nickel were present in some alloys, affecting the microstructure. The microstructure was investigated at the delivery state of spray-compacted material as well as for a wide range of welding speeds ranging from 0.5 to 10 m/min, respectively. The impact of speed on phase composition and morphology was studied at different disequilibrium solidification conditions. At high welding velocity, a close-meshed network of eutectic Al-Si-composition was observed, whereas the matrix is filled with nearly pure aluminum, helping to diminish the thermal stress during accelerated solidification. Primary solidified silicon was found, however, containing considerable amounts of aluminum, which was not expected from phase diagrams obtained at the thermodynamic equilibrium. View Full-Text


Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Keramische Werkstoffe und Technologien (IAM-KWT)
Institut für Mikroverfahrenstechnik (IMVT)
Publikationstyp Zeitschriftenaufsatz
Jahr 2016
Sprache Englisch
Identifikator DOI: 10.3390/met6120295
ISSN: 2075-4701
URN: urn:nbn:de:swb:90-624455
KITopen ID: 1000062445
HGF-Programm 37.03.02; LK 01
Erschienen in Metals
Band 6
Heft 12
Seiten 295
Lizenz CC BY 4.0: Creative Commons Namensnennung 4.0 International
Bemerkung zur Veröffentlichung Gefördert durch den KIT-Publikationsfonds
Schlagworte hypereutectic aluminum alloy, DISPAL, laser welding, nonequilibrium solidification
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