Synthesis of precipitation-strengthened Al-Sc, Al-Zr and Al-Sc-Zr alloys via selective laser melting of elemental powder blends

Jennifer A. Glerum, Christoph Kenel, Tao Sun, David C. Dunand*

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Selective laser melting is used to create Al-1.5Sc, Al-1.5Zr and Al-0.75Sc-0.75Zr (at.%) alloys from blends of elemental Al, Sc, and Zr powders. This study investigates elemental alloying elements (Sc and Zr) which are high-melting and highly reactive, unlike previous work which focused on more concentrated elemental additions of lower-melting, lower-reactivity Cu and Si to aluminum. High-speed in situ synchrotron x-ray imaging and diffraction show that the 20−30 μm Al, Sc, and Zr powders fully melt and sufficiently mix in the molten state to create, on solidification, a homogeneous distribution of primary, micron-size L12 precipitates (Al3Sc, Al3Zr, and Al3(Sc,Zr), respectively) and nucleate micron-size Al matrix grains, as confirmed by SEM imaging of cross-sections. A second laser pass, simulating a realistic additive-manufacturing build condition, fully remelts the initial volume which shows, after solidification, the same Al3(Sc,Zr) L12 primary micro-precipitates and very fine Al grains. After aging at 300−400°C, the alloys show large increases in hardness, consistent with an exceptionally high number density (1.4 × 1024 m−3) and volume fraction (2.5%) of secondary Al3(Sc,Zr) nano-precipitates with a Sc-rich core and Zr-rich shell, as measured via atom-probe tomography.

Original languageEnglish (US)
Article number101461
JournalAdditive Manufacturing
Volume36
DOIs
StatePublished - Dec 2020

Keywords

  • Additive manufacturing
  • Aluminum
  • Elemental blends
  • In situ diffraction
  • Selective laser melting

ASJC Scopus subject areas

  • Biomedical Engineering
  • Materials Science(all)
  • Engineering (miscellaneous)
  • Industrial and Manufacturing Engineering

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