Hierarchically strengthened aluminum-based superalloys

Clement Ekaputra and Dr. Jovid Rakhmonov;

co-advised by Dr. Jon-Erik Mogonye, U.S. Army Development Command Army Research Laboratory

Aluminum alloys are desirable for many energy applications; in particular in the transportation energy due to their high strength, low weight, and excellent corrosion/oxidation resistance. There is interest in extending the applications of aluminum alloys to elevated-temperature applications to reduce weight and energy consumption further. However, many commercial aluminum alloys lose their strength rapidly at elevated temperatures, due to coarsening of strengthening precipitates. As a result, there is a large body of research on alloying elements that do not degrade at high temperatures.

In particular, the Al-Ce system exhibits an Al-Al11Ce3 eutectic that creates a fine, interconnected eutectic microstructure upon solidification, and shows excellent creep resistance. Furthermore, there are a number of alloys strengthened by precipitates based on slow-diffusing elements, leading to increased coarsening and creep resistance. Alloys containing Al3(Sc,Zr) L12 nanoprecipitates, and α -Al(Mn,Mo)Si submicron precipitates are of particular interest.

Thus far, most studies focus on alloys strengthened by one precipitate population. We aim to combine three precipitate populations at different length scales - the Al11Ce3 micron-scale intermetallic, α -Al(Mn,Mo)Si submicron precipitates, and Al3(Sc,Zr) L12 nanoprecipitates to achieve an alloy with superior creep and coarsening resistance. We therefore aim to investigate the effects of these elements on the microstructure as well as the room and elevated-temperature mechanical properties of this alloy. Furthermore, we will investigate the effects of processing by casting and selective laser melting.

A number of aluminum alloy systems feature coarsening-resistant precipitates, such as the Al-Ce, Al-Sc-Zr, and Al-Mn-Mo-Si systems. The aim of this study is to investigate the effects of combining these elements into a single alloy system, and design alloys for casting and selective laser melting with excellent high-temperature mechanical performance.

Related Publications

  1. S. Griffiths, M.D Rossell, J. Croteau, N.Q. Vo, D.C. Dunand, C. Leinenbach "Effect of Laser Rescanning on the Grain Microstructure of a Selective Laser Melted Al-Mg-Zr Alloy" Materials Characterization, 143, 34-42, 2018.
  2. S. Griffiths, J. Croteau, M.D. Rossell, R. Erni, A. De Luca, N.Q. Vo, D.C. Dunand, C. Leinenbach "Coarsening- and Creep Resistance of Precipitation-Strengthened Al-Mg-Zr Alloys Processed by Selective Laser Melting" Acta Materialia, 188, 192-202, 2020.
  3. J. Glerum, T. Sun, C. Kenel, D.C. Dunand "Synthesis of Precipitation-Strengthened Al-Sc, Al-Zr and Al-Zr-Sc Alloys via Selective Laser Melting of Elemental Powder Blends" Additive Manufacturing, 36,101461, 2020.

Funding support

  1. U.S. Army Development Command Army Research Laboratory