Strength mechanisms and tunability in Al-Ce-Mg ternary alloys enabled by additive manufacturing

• Published in: Materials & design Vol. 231; p. 112009
• Main Authors: Nam, S., Simsek, E., Argibay, N., Rios, O., Henderson, H.B., Weiss, D., Moore, E.E., Perron, A.P., McCall, S.K., Ott, R.T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 01.07.2023; Elsevier
• Subjects: Additive manufacturing; Al-Ce alloys; Combinatorial approach; Directed-energy deposition; MATERIALS SCIENCE; Mechanical properties; Mechanical properties; Directed-energy deposition; Additive manufacturing; Al-Ce alloys; Combinatorial approach
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2023.112009

[Display omitted] •DED with multiple feedstock powders enables large composition ranges of potential AM alloys to be rapidly synthesized.•Microhardness measurements show relatively good agreement with predicted strengths obtained from the different strengthening models.•The microhardness measurements show good agreement with the ultimate tensile stress measured for the bulk samples synthesized by DED.•Solid solution hardening and Hall-Petch (based on cell size) are the major mechanisms controlling the alloy strength for the composition range we examined. Al-Ce-based alloys are promising candidates for additive manufacturing (AM) due to their hot-cracking resistance and because they do not require heat treatment to obtain precipitation strengthening. Rapid solidification rates enabled by AM methods can lead to enhanced mechanical properties; however, the strengthening mechanisms over large composition ranges were unclear. Here, combinatorial synthesis by directed-energy deposition (DED) and hardness measurements were used to rapidly map the composition-dependent strength of the ternary Al-Ce-Mg system. Tensile testing and microstructure characterization of selected compositions were performed to elucidate the compositional dependence of the strengthening mechanisms. Al11Ce3 precipitates were present in all cases, and the maximum hardness (1.25 GPa) was measured for the Al-8Ce-10Mg composition. A combination of (i) Hall-Petch strengthening, based on the FCC-matrix-phase cell size; (ii) particle strengthening, based on Al11Ce3 volume fraction and size; and (iii) solid-solution strengthening, based on Mg composition of the matrix phase, were used to account for the measured strengths. Vickers hardness is shown to correlate well with ultimate tensile strength in these alloys, highlighting the value of surface-based techniques for rapid screening.