In-situ alloying of AlSi10Mg+Si using Selective Laser Melting to control the coefficient of thermal expansion

Research output: Contribution to journalArticlepeer-review

Authors

  • Theresa Hanemann
  • Moritz Habschied
  • Martin Heilmaier

Colleges, School and Institutes

External organisations

  • Karlsruhe Institute of Technology

Abstract

Selective Laser Melting (SLM) was investigated as new processing route for strongly hypereutectic AlSi alloys for thermal management applications in space industry. Processing conditions, microstructure and thermal expansion behavior were analyzed for AlSi10Mg + Si alloys with 25 wt% and 50 wt% Si fabricated by in-situ SLM of powder mixtures. For both Si compositions parts with densities ≥ 99% could be achieved using laser power ≥ 275 W and scan speeds ≥ 1500 mm/s for the alloy containing 25 wt% Si and laser power of 400 W and scan speeds ≥ 1500 mm/s for the alloy containing 50 wt% Si. Considerable refinement of primary and eutectic Si was achieved for both Si compositions due to the high cooling rates of SLM. The mean particle size for the coarse primary Si of the 50 wt% Si containing alloy was below 10 μm. Additionally, unmolten Si powder particles were observed. Measurements of the coefficient of thermal expansion (CTE) showed the tailorability of CTE with adjustment of Si content. A decrease in CTE of 43% compared to pure Al was achieved at a total Si content of 50 wt%. Experimental data was close to model calculations based on the rule of mixture and the Turner model depending on the different microstructures of the two alloy compositions.

Details

Original languageEnglish
Pages (from-to)8-18
Number of pages11
JournalJournal of Alloys and Compounds
Volume795
Early online date28 Apr 2019
Publication statusPublished - 30 Jul 2019

Keywords

  • Hypereutectic Al-Si alloy, Microstructure, Selective laser melting, Thermal expansion