Grain refinement of Al-Mg-Sc alloy by ultrasonic treatment

In foundry practice, ultrasonic treatment has been used as an efficient technique to achieve grain refinement in aluminium and magnesium alloys. This article shows the strong effect of pouring temperature and ultrasonic treatment at various temperatures on the grain refinement of Al-1 wt% Mg-0.3 wt% Sc alloy. Without ultrasonic treatment, a fine grain structure was obtained at the pouring temperature of 700 °C. The average grain size sharply decreases from 487 ± 20 to 103 ± 2 μm when the pouring temperature decreases from 800 to 700 °C. Ultrasonic vibration proved to be a potential grain refinement technique with a wide range of pouring tem- perature. A microstructure with very fine and homogeneous grains was obtained by applying ultrasonic treatment to the melt at the temperature range between 700 and 740 °C, before pouring. Cavitation-enhanced hetero- geneous nucleation is the mechanism proposed to explain grain refinement by ultrasound in this alloy. Moreover, ultrasonic treatment of the melt was found to lead to cast samples with hardness values similar to those obtained in samples submitted to precipitation hardening, suggesting that ultrasonic treatment can avoid carrying out heat treatment of cast parts.This research was supported by The Project Bridging The Gap, funded by the Erasmus Mundus External Cooperation Window Programme. Acknowledgements also to the University of Minho, for the provision of research facilities

AlSi2Sc2 intermetallic formation in Al-7Si-0.3Mg-xSc alloys and their effects on as-cast properties

The influences of 0–0.65 wt% Sc additions on microstructure evolution during solidification, and on as-cast tensile properties and fracture behavior have been investigated in Al-7Si-0.3Mg foundry alloys. The results show that the addition of Sc significantly refines both the primary α-Al grain size and the eutectic silicon particle size, and Sc also results in the formation of AlSi2Sc2 in up to two eutectic reactions. The as-cast yield strength was improved by the addition of Sc, however, at high Sc level (0.65 wt%) the ultimate tensile strength decreased, owing to the formation of relatively large AlSi2Sc2 crystals in the Al-AlSi2Sc2 eutectic. The fracture path in the tensile samples is shown to pass through the eutectic AlSi2Sc2 intermetallic and eutectic silicon. The Sc level should not be higher than 0.40 wt% Sc to avoid the deleterious effect of AlSi2Sc2

Charakterytyka stopu Al-Zn-In otrzymanego metodą przeciskania w kanale kątowym

Equal channel angular pressing (ECAP) is a technique that creates a high accumulated strain in metals and results in ultrafine-grained structure. In this study, Al-5Zn-0.02In was processed by ECAP at a room temperature using route Bc through an ECAP die (press angle of Φ = 100° and Ψ = 20°). The samples were subjected to ECAP with 1, 2, 3 and 4 passes. The processed specimens were characterized using electron backscatter diffraction (EBSD). The results confirmed the grain refinement of the alloy after ECAP to an average grain size less than 5 μm after 4-pass ECAP. The microhardness test shows that the hardness increased with the number of passes. The hardness of the cross-sectional area of the sample was similar to that tested along the pressing direction.Metoda przeciskania w kanale kątowym (ang. Equal channel angular pressing; ECAP) prowadzi do powstania bardzo wysokich naprężeń, w wyniku czego otrzymuje się ziarna o bardzo drobnej strukturze. W niniejszej pracy, stop Al-5Zn-0,02In wytwarzano metodą ECAP w temperaturze pokojowej, wykorzystując ścieżkę Bc przez matrycę ECAP (kąty krzywizny: Φ = 100° i Ψ = 20°). Próbki poddano ECAP z 1, 2, 3 i 4 przejściami. Otrzymane próbki badano metodą dyfrakcji elektronów wstecznie rozproszonych (ang. electron back scatter diffraction; EBSD). W stopie otrzymanym metodą ECAP z 4 przejściami, średnia wielkość ziaren wynosiła mniej niż 5 μm. Badania mikrotwardości wykazały, że twardość zwiększała się wraz z liczbą przejść. Twardość zmierzona w poprzek próbki byłą porównywalna do tej mierzonej wzdłuż osi nacisku

Enhancing ambient and elevated temperature performance of hypoeutectic Al–Ce cast alloys by Al3(Sc,Zr) precipitate

This study explored the consequences of incorporating Sc and Zr into hypoeutectic Al–9Ce cast alloys, specifically investigating their influence on microstructure and mechanical properties. The findings demonstrated the significant reduction in the grain size of the Al–9Ce alloy while successfully maintaining the distinctive shape of the eutectic Al11Ce3 phase through the incorporation of Sc and Zr additions. During aging treatments, Al3(Sc,Zr) coherent precipitates formed both at the interface between the α-Al and Al11Ce3 phases and within the α-Al matrix. Remarkably, this led to optimal hardness achieved within a short duration of 3 h at 350 °C. Peak-aged quaternary Al–9Ce–xSc–yZr alloys showed significantly better tensile strength than the binary Al–Ce alloy at both ambient and elevated temperatures. Overall, the study underscored promising prospects of Al–Ce–Sc–Zr alloys for use in high-temperature applications, as they exhibited enhanced mechanical properties

Enhancing ambient and elevated temperature performance of hypoeutectic Al–Ce cast alloys by Al3(Sc,Zr) precipitate

Copyright © 2023 The Authors. This study explored the consequences of incorporating Sc and Zr into hypoeutectic Al–9Ce cast alloys, specifically investigating their influence on microstructure and mechanical properties. The findings demonstrate the significant reduction in the grain size of the Al–9Ce alloy while successfully maintaining the distinctive shape of the eutectic Al11Ce3 phase through the incorporation of Sc and Zr additions. During aging treatments, Al3(Sc,Zr) coherent precipitates formed both at the interface between the α-Al and Al11Ce3 phases and within the α-Al matrix. Remarkably, this leads to optimal hardness achieved within a short duration of 3 h at 350 °C. Peak-aged quaternary Al–9Ce-xSc-yZr alloys show significantly better tensile strength than the binary Al–Ce alloy in both ambient and elevated temperatures. Overall, the study underscores promising prospects of Al–Ce-Sc-Zr alloys for use in high-temperature applications, as they exhibit enhanced mechanical properties.A.M. acknowledges the financial support from King Mongkut's University of Technology Thonburi and the National Science and Technology Development Agency through the Petchra Pra Jom Klao Doctoral Scholarship KMUTT-NSTDA (Grant No. 1/2565). P.P. and C.L. acknowledge the financial support from Thailand Science Research and Innovation (TSRI) under Fundamental Fund 2023 (Project: Advanced Materials and Manufacturing for Applications in New S-curve Industries). D.E. acknowledges the financial support from EPSRC (UK) under the project grant PAAM (EP/W00593X/1)