Selective laser sintering/melting (SLS/SLM) of pure Al, Al-Mg, and Al-Si powders

Effect of processing conditions and powder properties

    Research output: Contribution to journalArticle

    156 Citations (Scopus)

    Abstract

    Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser-materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al-Mg, and Al-Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps' boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12-16 J/mm2 was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al-12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.

    Original languageEnglish
    Pages (from-to)1387-1405
    Number of pages19
    JournalJournal of Materials Processing Technology
    Volume213
    Issue number8
    DOIs
    Publication statusPublished - 2013

    Fingerprint

    Selective Laser Sintering
    Powder
    Melting
    Powders
    Sintering
    Lasers
    Oxides
    Processing
    Aluminum
    Oxide films
    Alloying
    Energy Density
    Surface Morphology
    Thermal Expansion
    Mullite
    Magnesium
    Coalescence
    Silicon
    Solidification
    Uniform distribution

    All Science Journal Classification (ASJC) codes

    • Ceramics and Composites
    • Modelling and Simulation
    • Computer Science Applications
    • Metals and Alloys
    • Industrial and Manufacturing Engineering

    Cite this

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    title = "Selective laser sintering/melting (SLS/SLM) of pure Al, Al-Mg, and Al-Si powders: Effect of processing conditions and powder properties",
    abstract = "Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser-materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al-Mg, and Al-Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps' boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12-16 J/mm2 was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al-12 wt{\%} Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.",
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    AB - Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser-materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al-Mg, and Al-Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps' boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12-16 J/mm2 was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al-12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.

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