This work seeks to study promising oxide dispersion strengthened (ODS) alloys identified by Northwestern University (NU) using in-situ techniques at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The primary work will be carried out by Ms. Jennifer Glerum, on the behalf of Northwestern, and supplement efforts of the LDRD “Advanced Additive Manufacturing of Metal Alloys” led by A. Greco of ANL. ODS alloys are a class of materials that offer an unmatched combination of deformation-, creep-, coarsening-, oxidation- and corrosion resistance at temperatures up to 1,000 °C. However, while these fundamental material properties are exceptionally well suited to power generation and engines, the manufacture of components using ODS alloys are currently subject to severe economic and technical barriers. Conventional wisdom is that powder metallurgy (PM) is the only available method to create ODS Al-superalloys from powders to which oxides were added via ball milling: if these composite powders were melted, their oxide dispersoids are lost via one or more of coarsening, dissolution, agglomeration into inter-dendritic space, and floating to the surface of the ingot (‘slagging”). In the current state-of-the-art, ODS aluminum alloys are thus exclusively made via PM (e.g., hot extrusion or hot isostatic pressing), a method which however has the following limitations: (i) high cost; (ii) only simple geometries can be produced that are also difficult to machine; (iii) parts cannot be repaired via local re-melting; (iv) grains are very small, pinned by oxides, and thus often not very creep resistant; (v) ductility is low. Furthermore, ODS aluminum parts, after PM, are difficult to finish with traditional machining techniques (drilling, milling, grinding) due to their high strength and limited ductility. There is no commercially-available ODS aluminum alloys due to these manufacturing challenges. Very recently, at Empa, a novel ODS TiAl (titanium aluminide) alloy was developed within the EU-FP7 project “OXIGEN” that could be melted and rapidly solidified into complex shapes via powder-bed and blown powder additive manufacturing (AM), while maintaining the oxide dispersoids finely dispersed within grains, with only minor dissolution or coarsening. This breakthrough was carried out in demonstration mode, with only one oxide species (Y2O3) and only one concentration (0.2 wt.%) considered. In the same project, commercial solid-solution-strengthened Ni alloys (Inconel 625 and Haynes 230) were milled into powders with nano-sized Y2O3 dispersoids, and successfully consolidated using selective laser melting (SLM) [4,5]. We seek here to capitalize immediately upon this breakthrough by focusing now on the more complex (and more commercially significant) ODS-aluminum-base superalloys, which can be further strengthened by L12 precipitates upon aging after solidification, and whose grain structure is fundamentally important for creep resistance. Here, we propose to demonstrate, for the first time, SLM of precipitation- and oxide-dispersion strengthened Al-base superalloy powders, creating bulk specimens with a unique and tunable combination of dispersoids, precipitates, and grain microstructure, while also maintaining the desirable aspects of additive manufacturing (rapid processing, extreme part geometry flexibility, low buy-to-fly ratio etc.). This fundamental study will be carried out on the simplest possible L12-precipitate-forming Al-ODS superalloy (Al-Sc-O and Al-Zr-O alloys with Al3(Sc/Zr) precipitates and Al2O3 di
|Effective start/end date||12/21/17 → 9/30/18|
- UChicago Argonne, LLC, Argonne National Laboratory (3J-30081-0070A)
- Department of Energy (3J-30081-0070A)
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