Comparison of the ageing behaviour of PM 2124 Al alloy and Al-SiCp metal-matrix composite

M.P. Thomas, J.E. King

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The ageing response of 2124 Al-SiC particulate metal-matrix composite (MMC) and unreinforced alloy has been examined using hardness measurements and Arrhenius analysis. The formation of phases during precipitation has been studied using differential scanning calorimetry (DSC). The MMC exhibits accelerated ageing compared to unreinforced alloy, due to enhanced S′ formation. The activation energy for diffusion is lower in the MMC than in the unreinforced alloy. DSC scans show Guinier-Preston B (GPB) zone nucleation to occur at a lower temperature in the MMC, whilst the total volume of GPB zones formed is smaller than in the unreinforced alloy. A model has been proposed to explain the GPB zone formation behaviour, in which ease of GPB zone nucleation varies within the MMC, as a function of ageing time and of position within the matrix. S′ formation is enhanced in the MMC because of improved diffusion and a large increase in density of heterogeneous nucleation sites compared to the unreinforced alloy. © 1994 Chapman & Hall.
    Original languageEnglish
    Pages (from-to)5272-5278
    Number of pages7
    JournalJournal of Materials Science
    Volume29
    Issue number20
    DOIs
    Publication statusPublished - 15 Oct 1994

    Keywords

    • aging of materials
    • aluminum alloys
    • aluminum powder metallurgy
    • calorimetry
    • diffusion in solids
    • grain boundaries
    • grain growth
    • hardness
    • mathematical models
    • silicon carbide
    • differential scanning calorimetry
    • Guinier-Preston B (GPB) zone nucleation
    • metallic matrix composites

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