Changes in the microstructure and mechanical properties of additively manufactured AlSi10Mg alloy after exposure to elevated temperatures

Journal Article · Thu Mar 15 04:00:00 EDT 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2018.01.028· OSTI ID:22804926

Michaela, Fousova; Drahomír, Dvorsky ^[1]; Alena, Michalcova; Dalibor, Vojtech ^[1]

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1. Department of Metals and Corrosion Engineering, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6 (Czech Republic)

Highlights: • Elevated temperatures above 120 °C brought changes to the AM AlSi10Mg alloy. • A maximum hardness state obtained at 160 °C/5 h was thoroughly tested. • Hardness increased by 15% and TYS by 5%, but elongation dropped by 60%. • Pure Si precipitates were responsible for the observed changes. - Abstract: The additive manufacture (AM) of the AlSi10Mg alloy has become the subject of considerable attention, especially for production of complex parts in engines. Because such parts can be exposed to elevated temperatures during operation, material stability is very important, but as yet little is known about it in relation to AM. Here, we studied changes of the AlSi10Mg alloy produced by selective laser melting (SLM) after its exposure to temperatures between 120 and 180 °C. At each temperature, hardness evolution was measured, with hardness increasing over time. The maximum hardness state obtained at 160 °C was selected for further studies comprising microstructural analysis by scanning and transmission electron microscopy, chemical composition analysis and mechanical properties assessment. Transmission microscopy revealed nano-scale acicular precipitates that caused a slight increase in the yield strength of the alloy together with a significant drop in elongation. Electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) showed that the precipitates surprisingly consisted of pure Si. To provide a comparison, conventional regimes of heat treatment (stress-relief and T6) were applied. Despite a considerable loss in mechanical performance, thermal instability was no longer observed. Overall, our results indicate that operating temperatures are a key factor in ensuring the smooth operation of AM parts of the AlSi10Mg alloy. In respect to that, we offer recommendations for their industrial use.

• OSTI ID: 22804926
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 137; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
ELONGATION
ENERGY-LOSS SPECTROSCOPY
HARDNESS
HEAT TREATMENTS
MAGNESIUM COMPOUNDS
MELTING
MICROSTRUCTURE
PERFORMANCE
PRECIPITATION
RECOMMENDATIONS
SCANNING LIGHT MICROSCOPY
SILICON COMPOUNDS
STABILITY
STRESSES
TERNARY ALLOY SYSTEMS
TRANSMISSION ELECTRON MICROSCOPY
YIELD STRENGTH