Scandium Extraction and Use in Aluminum Alloys: Scandium Containing Aluminum Alloys
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Timothy Langan, Sunrise Energy Metals; Samuel Wagstaff, Oculatus Consulting; Phil Chataigneau, Ppk Group Australia / Pdu Inc. ; Efthymios Balomenos, Mytilineos S.A.; Thomas Dorin, Deakin University; M. Akbar Rhamdhani, Swinburne University of Technology; Dimitrios Filippou, Rio Tinto Iron & Titanium; Henk van der Laan, V.I.C. Van der Laan International Consultancy BV; Frank Palm, Airbus Defence and Space GmbH
Tuesday 8:00 AM
March 21, 2023
Room: 30D
Location: SDCC
Session Chair: Timothy Langan, Sunrise Energy Metals
8:00 AM Introductory Comments Timothy Langan
8:05 AM Keynote
Formation of Al3Sc Dispersoids and Associated Strengthening Mechanisms: Thomas Dorin1; Lu Jiang1; Timothy Langan2; 1Deakin University; 2Sunrise Energy Metals
One of the main use of scandium is as an addition element in aluminum alloys as it results in significant improvement of a number of key properties including strength, corrosion resistance and formability. The benefits from scandium comes from the various influences it has on the alloys’ microstructure which can be summarized as four main effects, grain refinement, increased recrystallisation temperature, dispersoid strengthening and nucleation of strengthening phase. These mechanisms will be reviewed and the formation mechanisms of the L12 Al3Sc phase will be discussed. Optimizing the size and number density of Al3Sc is of crucial importance to get the maximum strengthening benefits from Sc additions. The heat treatment strategies to generate fine dispersions of dispersoids will be reviewed and the impact of Al3Sc on the breakdown of the solid solution in different alloy systems will be explored. Finally the addition of Zr in combination with Sc will be discussed.
8:55 AM Invited
Use of Sc to Improve the Properties of AA5083 Cast and Rolled Products: Paul Rometsch1; Jerome Fourmann1; Emad Elgallad2; X.-Grant Chen2; 1Rio Tinto Aluminium; 2University of Québec at Chicoutimi
The properties of 5xxx aluminum alloys can be improved with small additions of Sc. When Sc and Zr are added to 5xxx alloys, the alloys become heat-treatable as Al3(Sc,Zr) nanoprecipitates form at 300-400°C. However, the heat treatment and thermo-mechanical processing (TMP) need to be adapted to maximize the value of the Sc addition. In this work, AA5083 slabs were DC cast with and without minor additions of Sc and/or Zr. The room/elevated temperature mechanical properties of the cast materials were evaluated after various annealing and homogenization treatments. Samples were then hot and cold rolled with different TMP treatments. The microstructure, room temperature mechanical properties and corrosion performance were evaluated for selected tempers. It was evident that the properties could be improved significantly with small additions of Sc, but that this depends very much on the amount of Sc and on the processing parameters.
9:20 AM
Efficiency of Sc for Strengthening and Formability Improvement of 5XXX BiW Sheets: Alexander Gradoboev1; Margarita Nikitina1; Dmitriy Ryabov1; Roman Vakhromov1; Aleksandr Krokhin2; Viktor Mann2; Dror Shaked1; 1Lmti Llc (Uc Rusal); 2UC RUSAL
The use of aluminum makes it possible to reduce the weight of the car, thereby improving the environmental friendliness of transport by reducing CO2 emissions. Rolling sheets made of 5182 alloy are widely used for the manufacture of BIW parts manufactured by deep drawing. However, to increase the weight efficiency of the car it is necessary to develop an alloy with higher mechanical properties without losing processability. The results of previous studies of 5XXX series alloys showed that additives of Scandium, Zirconium and other REM lead to a significant increase in strength characteristics. The work presents the results of studies of the influence of small additives of Scandium and other REM on the mechanical and technological properties of alloys based on 5182, as well as the dependencies of changes in the level of mechanical and technological properties on rolling and heat treatment modes are established.
9:45 AM Break
10:00 AM
Effect of Sc and Zr Additions on Dispersoid Microstructure and Mechanical Properties of Hot-rolled AA5083 Alloys: Ahmed Algendy1; Kun Liu1; Paul Rometsch2; Nick Parson2; X.-Grant Chen1; 1University of Quebec at Chicoutimi; 2Rio Tinto Aluminum
5xxx aluminum alloys are traditionally considered non-heat-treatable. With the addition of Sc/Zr, two kinds of dispersoids (Mn-dispersoids and Al3(Sc,Zr)) were formed during heat treatment. The effect of Sc additions (0.08–0.43 wt.%) on the dispersoids and mechanical properties of hot-rolled sheets was investigated. The results showed that tensile properties initially increased with increasing Sc addition. The yield strength (YS) and ultimate tensile strength (UTS) of an alloy with 0.16 wt.% Sc reached 295 and 411 MPa, respectively, showing improvements of 30% in YS and 11.8% in UTS compared to the base alloy. However, with a further increase of Sc, the tensile properties declined owing to the formation of a line/fan-shaped microstructure associated with discontinuous Al3(Sc,Zr) precipitation during solidification. The evolution of Al3(Sc,Zr) and Mn-dispersoids during heat treatment and hot rolling was characterized using transmission electron microscopy. Their influence on the mechanical properties of hot-rolled AA5083 alloys was discussed.
10:25 AM
Effect of Cooling Rate on W-phase Formation in Al-Cu-Sc Alloys: Austin DePottey1; Lu Jiang2; Thomas Dorin2; Thomas Wood1; Timothy Langan3; Paul Sanders1; 1Michigan Technological University; 2Deakin University; 3Sunrise Energy Metals
Aluminum-copper-scandium alloys show significant potential for high strength applications; however, the formation of the detrimental W phase (nominally Al8Cu4Sc) has prevented commercial adoption. There is not a strong consensus as to what conditions lead to the formation of W phase, but two key factors are the cooling rate during solidification and the homogenization heat treatment. In this work, the effect of cooling rate on the formation of W phase in Al-Cu-Sc alloys is investigated utilizing wedge molds that produce solidification rates from ~0.25-100 K/s. Samples are examined in both the as-cast state and following homogenization and aging treatments.
10:50 AM Invited
Solute Clustering during Natural Ageing in Al-Cu-(Sc)-(Zr) Alloys: Lu Jiang1; Kathleen Wood2; Robert Knott2; Anna Sokolova2; Timothy Langan3; Thomas Dorin1; 1Deakin University; 2ANSTO; 3Sunrise Energy Metals
The present work investigates solute clustering during natural ageing in Al-4wt.%Cu alloys with and without Sc and Zr. The alloys were heat treated to form Al3(Sc, Zr) dispersoids before being solutionised at 500, 520 and 540°C followed by water quenching. Small-angle neutron scattering (SANS) was used to measure the size distribution of Al3(Sc, Zr) dispersoids in the Sc and Zr containing alloy. Clustering kinetics during natural ageing was quantified in-situ with small-angle x-ray scattering (SAXS). The in-situ SAXS results show that the presence of Al3(Sc, Zr) dispersoids significantly alters the solute cluster formation during natural ageing in the Al-Cu alloys. The altered natural ageing behaviour is explained by the presence of vacancies that is strongly influenced by the presence of Al3(Sc, Zr) dispersoids and solution treatment temperature. Atom probe tomography (APT) and transmission electron microscopy (TEM) are also used to reveal the underlying mechanism complementarily with the SAS results.
11:15 AM
Effect of Zr and Sc on Intermetallic Morphology and Hardening of an Al-Fe Alloy: Suwaree Chankitmunkong1; Dmitry Eskin2; Chaowalit Chaowalit Limmaneevichitr3; Phromphong Pandee3; Onnjira Diewwanit3; 1King Mongkut's Institute of Technology Ladkrabang; 2Brunel University London; 3King Mongkut's University of Technology Thonburi
We studied the effect of zirconium and scandium on an Al-7 wt% Fe cast alloy with potential heat- and wear-resistant applications. An addition of 0.2% Zr resulted in thinning of primary Al3Fe particles; while an addition of 0.15% Zr and 0.15% Sc changed the morphology of primary intermetallics from needles to flower-like shape. While the addition of Zr did affect the properties, the Zr+Sc joint additions increased the hardness of the as-cast Al-Fe alloy. The hardness of the base alloy increased upon annealing from 40 to 80 HV (450 °C, 20 h) and to 110 HV (350 °C, 20 h). The wear resistance of the Al-Fe alloy was also improved by Zr and Sc addition, especially after annealing. The observed effects are likely to be linked to the supersaturation of Zr and Sc in the aluminum solid solution during solidification and precipitation of dispersoids during annealing.