Scandium Extraction and Use in Aluminum Alloys: Scandium Extraction and Use in Aluminum Alloys
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Timothy Langan, Sunrise Energy Metals; Frank Palm, Airbus Defence and Space GmbH; Thomas Dorin, Deakin University; Paul Rometsch, Rio Tinto Aluminium; Henk van der Laan, V.I.C. Van der Laan International Consultancy BV; Efthymios Balomenos, Mytilineos S.A.; M. Akbar Rhamdhani, Swinburne University of Technology; Samuel Wagstaff, Oculatus Consulting

Tuesday 8:00 AM
March 5, 2024
Room: Windermere X-3
Location: Hyatt

Session Chair: Timothy Langan, Sunrise Energy Metals

8:00 AM  
The Role of New Aluminium-Scandium Alloys for Emission Reduction in Various Sectors: Thomas Dorin1; Timothy Langan2; 1Deakin University; 2Sunrise Energy Metals
    The rapid growth of industrialization and transportation has led to increasing concerns over greenhouse gas emissions and their impact on climate change. As a result, industries are constantly seeking innovative solutions to reduce their carbon footprint. One promising avenue is the integration of new aluminium-scandium (Al-Sc) alloys, which offer unique properties and capabilities to address emissions reduction in various sectors. This paper delves into the role of Al-Sc alloys in four key areas: automotive, shipbuilding, additive manufacturing, and high-voltage (HV) conductors. In the automotive sector, Al-Sc alloys present an opportunity to streamline production and minimize emissions by consolidating the number of alloys used in vehicle construction. For instance, by replacing conventional 6xxx-series alloys with 5xxx-series+Sc for both inner and outer panels, it would reduce the number of alloys in a vehicle, making it more readily recyclable. In shipbuilding, the adoption of 5xxx-series+Sc alloys proves advantageous as it can enhance weld strength and mitigate sensitization issues. Consequently, vessels' service life could be extended while reducing overall weight, leading to notable emissions reductions. Furthermore, the potential of Al-Sc alloys in additive manufacturing (AM) is explored. Tailored alloy compositions developed for AM applications, with strategic scandium and zirconium content can enable in-situ precipitation during the AM process. This can eliminate the need for post-aging, making large-scale AM more feasible and cost-effective while promoting emission reductions. Lastly, we discuss the application of Al-Sc alloys in HV conductors. By incorporating scandium, these conductors can achieve increased strength without significant compromise to electrical conductivity, fostering a greener power transmission infrastructure. In conclusion, the utilization of new aluminium-scandium alloys presents a promising pathway to curbing emissions in multiple industries, signalling a transformative shift towards more sustainable practices.

8:50 AM  
Sc-containing Al-Si-Mg (6xxx) Alloys for Automotive Extrusions: Timothy Langan1; Thomas Wood2; Paul Sanders2; Avishan Shomali3; 1Sunrise Energy Metals; 2Michigan Technological University; 3Kaiser Aluminum
    Our work focuses on improving manufacturability and performance of Al-Si-Mg 6xxx series alloys for structural automotive components. Scandium is the most potent strengthening element in aluminum alloys but interactions between Sc and Si have limited use of Sc in high Si-containing alloys (6xxx). We demonstrate modified heat treatment schedules for precipitation of potent Sc-containing dispersoids which are stable during extrusion and processing. Trace scandium additions increase strength and tear resistance in lightly alloyed 6xxx alloys and reduce extrusion and heat-treating costs relative to alloys with comparable strength and tear resistance. In one example, an Al-0.5Si-0.5Mg alloy with an 0.9wt% Sc addition increased T6 yield strength from 40ksi to 54ksi with ductility only decreasing from 21 to 18%. The role of casting and homogenization on precipitation of these stable Sc-containing dispersoids will be discussed.

9:15 AM  
Investigation of the Mechanical Properties of Flat Rolled Products of Aluminium Alloys Al-Mg-Sc Under Various Deformation Processing Modes: Alexander Alabin1; Sergey Valchuk1; Alexander Krokhin1; Dror Shaked1; Martijn Vos2; 1UC RUSAL; 2Rusal
    In this paper, the influence of various modes of deformation processing on the properties of flat rolled products of alloys 5081 and 5181 base of the Al-Mg-Sc system was studied. It is shown that the level of strength properties of annealed sheets depends on the degree of deformation during hot and cold rolling. A low sensitivity of the material containing 0.1 wt.% scandium to the degree of deformation during rolling, in relation to the material containing 0.03 wt.% scandium, has been found.

9:40 AM Break

9:55 AM  
Effect of Sc and Zr Microalloying on Grain Structure After Hot Deformation and Brazing in 3xxx Alloys: Alyaa Bakr1; Paul Rometsch2; X.-Grant Chen1; 1UQAC; 2Arvida Research and Development Centre, Rio Tinto Aluminium
    A series of Al-Mn 3xxx alloys are used in the fabrication of multi-port extruded (MPE) tubes for aluminium heat exchangers. The industrial manufacture for these tubes consists of homogenization, extrusion, sizing, and brazing. The combination of sizing and brazing could result in abnormally coarsened grains that have negative impacts on the in-service performance of MPE tubes. In this work, we simulated the industrial manufacturing process of the MPE tubes. The 3xxx alloy micro alloyed with 0.08 wt% Sc and 0.09 wt% Zr was assessed with respect to the grain structures after hot deformation and brazing, a comparison was made with a base 3xxx alloy free of Sc and Zr. EBSD maps after hot deformation showed that the Al-0.08S-0.09Zr alloy exhibited more resistance towards recrystallization resistance. After the simulated high-temperature brazing at 605 C, the base alloy suffered from abnormal grain growth, whereas the Al-0.08Sc-0.09Zr alloy exhibited an elongated recrystallized microstructure.

10:20 AM  
Hot Deformation Behavior and Post Brazing Grain Structure of Dilute Al-(Sc-Zr) Alloys for Brazed Heat Exchangers: Alyaa Bakr1; Paul Rometsch2; X.-Grant Chen1; 1UQAC; 2Arvida Research and Development Centre, Rio Tinto Aluminium
    In this work, dilute Al-0.07Sc and Al-0.07Sc-0.09Zr alloys were assessed with respect to the hot deformation and the post brazing grain structure and compared with the base 1xxx alloy. The flow curves of the hot compression tests showed that the Al-Sc-Zr alloys exhibited higher flow stresses compared to the base alloy. The microstructure of the deformed samples in all three investigated alloys exhibited a recovered microstructure, but the dilute Al-Sc-Zr alloys showed an improvement in the resistance to dynamic recovery. EBSD maps after a simulated high temperature braze showed that the microstructure of the base 1xxx alloy suffered from severe grain coarsening. Few coarsened grains were observed in the recrystallized microstructure of the Al-0.07Sc alloy after brazing, while no severely coarsened grains were observed in the microstructure of the Al-0.07Sc-0.09Zr alloy after brazing, indicating an improvement in the resistance to grain coarsening due to the addition of Sc and Zr.

10:45 AM  
Investigating the Influence of Iron Content on the Microstructure and Mechanical Properties of a High Strength Al-alloy for Additive Manufacturing Additive Manufacturing: Matteo Turani1; Jannic Walter1; Paulo Davi Borges Esteves1; Enrico Tosoratti1; Adriaan Spierings2; Markus Bambach1; 1ETH Zurich; 2inspire AG
     Scalmalloy, a Sc,Zr-modified Al-alloy tailored for additive manufacturing, shows great promise due to its exceptional strength, low density, and corrosion resistance. This study investigates the influence of Fe, a common impurity in secondary aluminum, on the microstructure, mechanical properties, and sustainability of Scalmalloy processed using Laser Powder Bed Fusion (LPBF).Three Scalmalloy variants (pristine, 1.5 and 3.5 wt% Fe) were analyzed. Electron microscopy and X-ray diffraction revealed the presence of stable/metastable Fe precipitates and their impact on the precipitation of Sc,Zr-rich primary phases. Mechanical property evaluations demonstrated increased tensile strength and hardness, albeit with reduced ductility, as Fe content increased. Furthermore, compression tests at elevated temperatures showcased the alloy thermal stability. In conclusion, this study explores the feasibility of processing Fe-contaminated aluminum feedstock through LPBF, promoting resource efficiency and reduced environmental impact.

11:10 AM  
How Can Europe Reduce Offshore Dependence of Its Supply Chain for Critical Metals like Scandium?: Henk van der Laan1; Beate Orberger; 1V.I.C. Van der Laan International Consultancy BV
    Europe uses around 25% of the World metal production, including critical metals like Sc, Mg, Ti, Sr, Nb and REE’s. However, just around 2 - 3% of the World metal production is actually manufactured in Europe, resulting in a huge imbalance. Critical metals are indispensable in the green transition for producing renewable energy. Most of these critical metals (Mg, Nb, Sc, Sr, and Ti) are for 100% imported. The dependence on imports can lead to supply disruptions and unacceptable high prices. An option for Europe is to focus on Industrial Symbiosis (IS) projects, in which waste streams from one industry are used as a feedstock for other industries. EU Magnesium, ScaVanger, Scale-up and Valore are examples of EU funded IS projects. In order to avoid future supply disruptions, like the 2021 Mg crisis, Europe needs to set up a European organised stockpile organisation for critical metals like Sc, Sr, Nb, Mg and Ti.

11:35 AM  
Behavior of Yttrium and Other Impurities in the Production of Scandium Oxide from Bauxite Residue: Alexander Suss1; Alexander Kozyrev1; Natalia Kuznetsova1; Alexander Damaskin1; Sergey Pishchalniko1; Andrey Panov1; Sergey Ordon2; Oleg Milshin3; 1RUSAL; 2RUSAL Engineering and Technology Center; 3RUSAL Management JSC
    Bauxites in the North of European Russia are characterized by a high scandium content (up to 350 ppm calculated as Sc2O3). Most of scandium is imbedded into the structure of aluminum-containing minerals, as well as into zircon ZrSiO4 and apatite. These minerals break down during the pressure digestion of the bauxites, so scandium is re-precipitated and sorbed on the surface of bauxite residue particles. UC RUSAL has develop and pilot tested the extraction of scandium oxide from bauxite residue using a sodium bicarbonate solution that enables to dissolve up to 50 % of scandium into the solution followed by precipitation of the concentrate and purification to obtain 99.0 % Sc2O3. The extraction uses actual liquors from alumina production and flue gases. Bauxites contain a number of REM elements (e.g. zircon, titanium, hafnium, copper, yttrium, thorium, etc.). Chemical behaviour of said REMs during the sodium bicarbonate digestion is similar to the behaviour of scandium. To obtain pure scandium oxide (2N) (Sc2O3 ≥ 99.0 wt.%) without radioactive impurities effective purification technology was developed. Moreover, resulting mutual neutralisation of some streams allows obtaining a high-grade REM concentrate. The additional advantage of this process lies in reducing the carbon footprint of alumina production due to the use of flue gases containing up to 8 vol.% CO2, as well as alkali neutralisation in the bauxite residue.