Directed energy deposition of AA7075 - effect of TiC nanoparticles on microstructure

Lucia Cobian Gonzalez, Jari Tuominen, Shahroz Ahmed, Madan Patnamsetty, Pasi Peura

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Abstract

AA7075 alloy is a high-strength aluminum alloy with properties enhanced by heat treatments. However, like most high-strength aluminum alloys, AA7075 is non-weldable, as it suffers from hot cracking when it is welded or additively manufactured with fusion techniques. A proposed way to reduce the hot cracking tendency is by refining the microstructure by adding nucleation enhancers. In this study, AA7075 powder feedstock was functionalized with 1.7 and 3.4 vol.% TiC nanoparticles, printed with laser-directed energy deposition (DED), subjected to T6 heat treatment, and characterized with optical and electron microscopy, electron backscatter diffraction (EBSD), and hardness measurements. Although TiC was not homogeneously distributed in the aluminum matrix, the addition of TiC successfully suppressed hot cracking by inhibiting dendritic growth produced by increased and more uniform nucleation, which resulted in refined equiaxed grains, and thus enhanced the printability of the material.
Original languageEnglish
Article number100341
JournalResults in Materials
Volume16
DOIs
Publication statusE-pub ahead of print - 19 Oct 2022
Publication typeA1 Journal article-refereed

Keywords

  • AA7075
  • laser-DED
  • nucleation enhancers
  • post-heat treatment
  • microstructure
  • additive manufacturing
  • Directed energy deposition

Publication forum classification

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