Next Article in Journal
The Effect of Tin Content on the Strength of a Carbon Fiber/Al-Sn-Matrix Composite Wire
Previous Article in Journal
Effect of Multi-Step Austempering Treatment on the Microstructure and Mechanical Properties of a High Silicon Carbide-Free Bainitic Steel with Bimodal Bainite Distribution
Previous Article in Special Issue
Microstructure and Phase Formation of Novel Al80Mg5Sn5Zn5X5 Light-Weight Complex Concentrated Aluminum Alloys
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Metals
Volume 11
Issue 12
10.3390/met11122056
metals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

The Casting Rate Impact on the Microstructure in Al–Mg–Si Alloy with Silicon Excess and Small Zr, Sc Additives

by
Evgenii Aryshenskii
1,
Maksim Lapshov
1,
Sergey Konovalov
1,*,
Jurgen Hirsch
1,
Vladimir Aryshenskii
2 and
Svetlana Sbitneva
3
1
Department of Metals Technology and Aviation Materials, Samara National Research University, Moskovskoye Shosse 34, 443086 Samara, Russia
2
Department of Metal Processing by Pressure, Samara National Research University, Moskovskoye Shosse 34, 443086 Samara, Russia
3
All-Russian Scientific Research Institute of Aviation Materials of the National Research Center, Kurchatov Institute, Radio 34, 105005 Moscow, Russia
*
Author to whom correspondence should be addressed.
Metals 2021, 11(12), 2056; https://doi.org/10.3390/met11122056
Submission received: 24 November 2021 / Revised: 13 December 2021 / Accepted: 15 December 2021 / Published: 19 December 2021
(This article belongs to the Special Issue Microstructure and Mechanical Properties of Aluminum Alloys)
Browse Figures
Versions Notes

Abstract

:
The study investigates the effect of casting speed on the solidification microstructure of the aluminum alloy Al0.3Mg1Si with and without the additions of zirconium and scandium. Casting was carried out in steel, copper, and water-cooled chill molds with a crystallization rate of 20 °C/s, 10 °C/s, and 30 °C/s, respectively. For each casting mode, the grain structure was investigated by optical microscopy and the intermetallic particles were investigated by scanning and transmission microscopy; in addition, measurements of the microhardness and the electrical conductivity were carried out. An increase in the solidification rate promotes grain refinement in both alloys. At the same time, the ingot cooling rate differently affects the number of intermetallic particles. In an alloy without scandium–zirconium additives, an increase in the ingot cooling rate leads to a decrease in the number of dispersoids due to an increase in the solubility of the alloying elements in a supersaturated solid solution. With the addition of scandium and zirconium, the amount of dispersoids increases slightly. This is because increasing the solubility of the alloying elements in a supersaturated solid solution is leveled by a growth of the number of grain boundaries, promoting the formation of particles of the (AlSi)3ScZr type, including those of the L12 type. In addition, the increase in the crystallization rate increases the number of primary nonequilibrium intermetallic particles which have a eutectic nature.

1. Introduction

Today, aluminum and its alloys are one of the materials with highest growth rates in demand and application [1,2,3,4,5,6,7,8]. Alloys of the 6xxx series (Al–Mg–Si) show the highest demand, especially in the automotive and aerospace industries [9,10]. This is due to the fact that they have many properties most suitable for automotive products, e.g., low weight, good strength, corrosion resistance, formability, and manufacturability [11,12,13,14,15,16,17,18]. Moreover, Al–Mg–Si alloys can be thermally hardened, which additionally raises their strength properties [19,20]. The alloys of the 6xxx group are divided into those where the mass ratio Mg/Si = 1.73 (i.e., the exact Mg2Si phase) is fulfilled, and where this ratio is more or less than 1.73. In the first stage, all of the Mg and Si alloy elements will be present in the Mg2Si particles under equilibrium crystallization conditions. Such alloys are called pseudo-binary alloys of the Al–Mg2Si system. In the second case, the alloys are called ‘with an excess of Mg’ or ‘an excess of Si’, respectively.
One way to further improve the performance characteristics of Al–Mg–Si alloys is through their complex alloying with scandium–zirconium elements. Aluminum alloys doped with complex scandium–zirconium additives have very high mechanical properties at room temperature due to the coherent nanosized Al3Sc(Zr) particles [21,22]. Besides, the scandium-doped (Sc) aluminum-based alloys have good welding characteristics, desirable creep, and corrosion resistance [23,24,25,26,27]. The combined additions of Sc and Zr also have a positive effect on the strength properties. Zr can replace part of Sc in Al3Sc, which will lead the Al3(Sc1-x, Zrx) dispersoids with the L12 crystal structure, besides Al3Sc [28,29,30,31].
In addition, joint doping with small additions of scandium and zirconium makes it possible to significantly refine the grains in aluminum alloys [32]. Reducing the grain size improves ductility, strength, and toughness at room temperature. In addition, there is also the potential to achieve a superplastic state.
However, doping by scandium does not in all cases lead to the increased strength properties of Al–Mg–Si alloys, since scandium forms a Sc2Si2Al compound with silicon which reduces the properties of the metal [33,34]. This problem is especially acute in alloys with excessed silicon. At the same time, an excess of Si in the pseudo-binary system Al–Mg2Si can have a positive effect on the strengthening of particles and, accordingly, on the mechanical properties. Therefore, it is promising to add Sc and Zr to alloys with high Si content. Some investigations show the positive effect of Sc and Zr additions to 6xxx-series alloys, even with an excess Si content [35,36]. However, such alloys require the careful selection of casting modes and multistage heat treatment, which makes it possible to sequentially obtain the strengthening particles (AlSi)3ScZr and β″ (Mg5Si6).
Controlling the casting rate allows for the control of the level of elements in a supersaturated solid solution, thereby facilitating the subsequent heat treatment and reducing the number of its stages. In addition, by changing the casting speed it is possible to achieve a modification of the grain structure and, consequently, to increase the mechanical properties. However, as the cooling rate during crystallization increases, the chance of the undesirable formation of eutectics increases as well.
This paper is devoted to studying the influence of the casting rate on the microstructure of the Al0.3Mg1Si alloy doped with small additions of Zr and Sc with a Mg/Si ratio of 0.3.

2. Test Methods

The cast alloys and the method of casting are shown in Table 1.
Alloys from high-purity metals: aluminum—99.8%, magnesium—99.9%, and master alloys Al12Si, Al–5%Zr, and Al–2%Sc were smelted in an electric induction resistance furnace in graphite crucibles. To study the effect of the crystallization rate, three types of chill molds were used: a steel chill mold (200 mm × 135 mm × 30 mm), a copper chill mold (80 mm × 40 mm× 20 mm), and a round copper chill mold (ø10 mm × 100 mm). The temperature during casting was 720–740 °C. Immediately before pouring the metal into the chill mold, the oxide was removed from the surface of the molten metal. The metal was poured at a uniform rate for all chill molds. The cooling rate was of the order of 2 °C/s for the steel chill mold, 10 °C/s and 30 °C/s for the copper chill molds of rectangular and circular cross-sections, respectively.
The grain size was determined on an Axiovert-40 MAT optical microscope, Carl Zeiss, Germany, in polarized light (the samples were prepared by electropolishing in a fluoroboron electrolyte before study) with the calculation of the average grain size by the secant method according to GOST 21073.
Microhardness studies were carried out on a digital stationary hardness tester according to the micro-Vickers method on the HV-1000 device, TIME Group Inc., Beijing, China. The tests were carried out by pressing a pyramidal diamond indenter with a specified force into the surface of the test piece. On each sample, 10 measurements were made in 5 different areas (values differing from the average by more than 10% were not taken into account).
Specific electrical conductivity was measured with a portable VE-17NTs device (measurement error no more than 2%), mailbox P-6409, Yekaterinburg, Russia.
The JEOL 6390A SEM (Akishima, Tokyo) was used for the electron microscopy to determine the size and chemical composition. The study of the chemical composition of the structural components was done by energy dispersive spectroscopy using the X-Max 80T detector (Oxford Instruments, Oxford, UK) in the energy range 0–10 keV (the energy resolution of the detector is 122 eV). The sample preparation technique consisted of mechanical grinding, polishing, and electropolishing. Electropolishing was carried out at temperatures of 85–110 °C and voltages of 10–30 V in an electrolyte of the following composition: 500 mL of H3PO4; 300 mL H2SO4; 50 g CrO3; 50 mL H2O.
The study was carried out on the Tecnai G2 F20 S-TWIN TMP transmission electron microscope (FEI, Hillsboro, OR, USA) with a thermal-field cathode at an accelerating voltage of 200 kV. The chemical composition of the fine dispersion participles was studied by the energy dispersive spectroscopy (EDS) method using the X-Max 80T detector in the energy range 0–10 keV. The energy resolution of the detector is 122 eV.

3. Results

The cooling rate was measured during crystallization and after crystallization until reaching the temperature of 30 °C and was calculated as the average rate over time. As expected, the largest difference in the cooling rate was detected during the crystallization process. The average rate was 2, 10, and 30 °C/s for steel, copper, and copper round chill molds, respectively.
Based on the results obtained during the metal cooling rate measurements when using chill molds of different types, the temperature dependence on the cooling time was plotted in Figure 1. Figure 1 shows the rate of the temperature drop after crystallization (660 °C), which is especially pronounced in case of the steel chill mold. The average cooling rate decreased by about three times and was about 0.7 °C/s for the steel chill mold, 3.2 °C/s for the copper one, and 8.1 °C/s for the copper round section. All data are summarized in Table 2.
The microstructures examined by optical microscopy are shown in Figure 2.
The Al0.3Mg1Si alloy, cast in the steel chill mold, consists of very large, up to 2–3 mm, arbitrarily directed dendritic grains, as shown in Figure 2a. When casting into the copper chill mold, directional crystallization occurs during growth and the further junction of the columnar crystal zones. As a rule, the crystals are directed towards heat dissipation, as shown in Figure 2b. As a result, a uniaxial granular structure is formed, which has much smaller sizes (400 µm) than in the first (steel) case. In the case of casting into the copper chill mold with the circular cross-section, the grains are even more refined. Their shape becomes significantly more equiaxed; however, these grains are still dendritic, as shown in Figure 2c. On the whole, the solidification behavior of the grains obeys a well-known pattern: the grain size decreases when the crystallization rate increases due to a larger number of nuclei formed [37].
Significant grain refinement is observed during the combined alloying with scandium and zirconium (Figure 2d–f). However, in the case of casting into the steel chill mold (Figure 2d), in general, dendritic structures with small inclusions of equiaxed grains are still observed. A completely equiaxed structure begins to form only during casting into the copper chill mold (Figure 2e). As expected, the strongest modification of the grain structure is observed in the chill mold of the round cross-section.
As can be seen from the graph, the grain size decreases continuously as the sample cooling rate increases (Figure 3). In all casting modes, the largest grains are observed in the Al0.3Mg1Si alloy. When cast into the steel chill mold, the grain size is 1370 μm. In the case of the rectangular copper chill mold, the grain size decreases to 420 μm, which also exceeds the value of the sample doped with Sc and Zr in this casting mode. The smallest grain size under various casting conditions is observed in the Al0.3Mg1Si0.3Sc0.15Zr alloy when casting it into the copper chill mold with the circular cross section (55 μm). At the same time, this value is 370 μm in the base alloy, which indicates a high potential in modifying the properties when Sc is combined with Zr.
It should be noted that the modification effect is generally lower than in higher doped alloys. This can be explained by the fact that the grain size itself without the additions of scandium and zirconium is initially significantly less than 400–600 μm in these alloys. However, in general a 6–8-time grain refinement is observed, as is the case in the alloys described in [32]. In addition, the effect of overcooling between the nucleus of the crystallization and the liquid phase caused by a large number of impurity elements will also affect the more effective modification [38].
The electrical conductivity decreases uniformly as the cooling rate increases in all samples (Figure 4), which indicates a corresponding (directly proportional) increase in electrical resistance (i.e., its inverse value). An increase in the electrical resistance occurs with an increase in the number of elements in solid solution in the alloys.
The highest electrical conductivity (29.8 mS/m) is observed in the Al0.3Mg1Si alloy at a cooling rate of 2 °C/s. When the cooling rate increases, the electrical conductivity decreases to 29.35 mS/m at 10 °C/s and to 28.35 mS/m at 30 °C/s. Thus, due to the absence of zirconium and scandium, additional phases are not generated in any casting mode.
When the alloying elements Sc and Zr are added to the Al0.3Mg1Si alloy, the electrical conductivity decreases by more than 2 mS/m due to the formation of Al9Fe2Si2, (Al, Si)3(Sc), Al3(Sc0.6Zr0.4), and Mg2Si phases. The effect of the casting (i.e., cooling) rate on the electrical conductivity due to this microalloying effect is much more significant than in the base alloy: 27.38 mS/m at a cooling rate of 2 °C/s, and 24.73 mS/m at a cooling rate of 30 °C/s.
The microhardness data and their dependence on the cooling rate are plotted in Figure 5. The decreased microhardness of the Al0.3Mg1Si alloy indicates that, with the increasing cooling rate, the fine particles are quenched into a supersaturated solid solution. A slight increase in the microhardness of the Al0.3Mg1Si alloy when increasing the casting rate to 30 °C/s is caused by the large number of primary nonequilibrium particles with a size of 0.5–1 µm. In Al0.3Mg1Si0.3Sc0.15Zr, this increase in microhardness indicates that intermetallic particles with a chemical composition close to (AlSi)3ScZr are formed.
Figure 6 shows the micrographs of the base alloy 0.3Mg1Si. The main phase characteristic of this alloy is Fe2Mg7Si10Al18. It has the form of large needle-shaped particles with a size of 10–20 µm. These intermetallic compounds are mainly of eutectic nature. Their origin can be explained as follows: the higher the supercooling, the faster the supersaturated solid solution crystallizes and the less saturated it becomes, thereby leaving more liquid for the eutectic reaction. The average size of intermetallic compounds decreases to 5–7 µm with increasing cooling rate, and they appear both inside and along the boundaries of the dendrites.
The Al0.3Mg1Si0.3Sc0.15Zr alloy contains a much larger number of intermetallic phases formed due to the addition of Sc and Zr (Figure 7). Four types of phases (Al9Fe2Si2, (Al, Si)3(Sc), Al3(Sc0.6Zr0.4), and Fe2Mg7Si10Al18) are identified in a specimen obtained by casting into the steel chill mold. The number of phases that can be identified declines when the cooling rate increases. For example, only two phases (Fe2Mg7Si10Al18 and Al9Fe2Si2) have been revealed when casting into the rectangular copper chill mold. At the highest cooling rate, achieved during casting into the mold of the circular variable cross-section, only one phase (Fe2Mg7Si10Al18) has been detected. However, this is not due to the reduction in the number of phases, but due to the rather small intermetallic compounds with a eutectic nature that appear with a size of only 1 μm. At the minimum cooling rate, the intermetallic compounds, which are located along the boundaries of the grains (in this case, an equiaxed structure), have a mainly acicular shape. When the cooling rate increases, the number of intermetallic compounds located mainly along the grain boundaries increases as well. In addition, small intermetallic particles located inside the grains appear. When the crystallization rate increases, the number of small intermetallic compounds with sizes of 0.5 ÷ 1 μm increases. This is due to the fact that the number of intermetallic compounds formed inside the large grains increases, but it is also due to the particles appearing at grain boundaries, and their length also increases as a result of grain refinement.
In the Al0.3Mg1Si alloy (Figure 8), there is a small amount of dispersoids of a sufficiently large size when casting in the steel chill mold. However, as one can see, when the casting rate (copper chill molds) increases, the size of the dispersoids decreases simultaneously with the increase in their number. This change is due to the fact that the number of grain boundaries increases, which serve as a nucleation site for the dispersoids during the ingot cooling after crystallization [39,40]. When Sc and Zr are added, the amount and size of dispersoids slightly decrease in comparison with pure Al0.3Mg1Si when casting into steel and copper chill molds, but the amount and size increase sharply during casting with intense cooling. Note that the sharp growth of the dispersed particles is primarily associated with the increased length of the grain boundaries due to the modification of the dendritic structure with small additions of Zr and Sc. Thus, increased solubility due to the increased cooling rate of the metal is not enough to restrain the precipitation of the dispersed particles. This is due to the increased length of the grain boundaries which serve as a nucleation site for their precipitation.
When casting into a steel chill mold, two types of particles are observed, namely, coherent (AlSi)3ScZr with dimensions of about 20 nm which have the L12-structure (Figure 9a). In addition, needle-shaped particles with the same chemical composition (AlSi)3ScZr are observed. They have a fan-shaped precipitation pattern (Figure 9a–c) and are formed at the grain boundaries as a result of their movement [41]. Their size ranges from 300 to 1200 nm. These particles have been repeatedly observed in aluminum alloys containing scandium [39,40]. It is also noteworthy that the coherent and needle-shaped particles are precipitated in different grains. In general, the observed pattern corresponds to the one previously observed in this alloy under similar casting conditions.
When the cooling rate increases, mainly the needle-shaped precipitates of the (AlSi)3ScZr-type particles are observed (Figure 10). The particle size itself decreases to 500–600 nm. Another difference is that the coherent (AlSi)3ScZr particles are observed in the same grains between the needle-shaped particles. Thus, the type of particle is not linked to individual grains at the given cooling rate.
When cooled into the cone, fine coherent and semicoherent nanoparticles with L12-sizes and a chemical composition of (AlSi)3ScZr can be observed. In addition, needle-shaped precipitates of the (AlSi)3ScZr particles are present. As in the case of cooling into the steel chill mold, these particles are entangled separately from the coherent and semicoherent particles. It should be noted that the differences in the (AlSi)3ScZr particle distribution can be associated with TEM restrictions on the area of the investigated surface, not with casting modes. The average grain size is 55 nm even at the fastest cooling rate. Therefore, even one crystallite cannot be fully investigated. It should also be noted that the cooling rate does not greatly affect the number of the (AlSi)3ScZr particles. Moreover, based on the microhardness indicators, we conclude that their number is increasing. It should be noted that in the case of the alloy without zirconium and scandium additions, the microhardness is reduced when cooling increases due to the increased solubility of alloying elements in the aluminum matrix. The explanation for the difference between these two alloys is the growing number of high-angle boundaries at the increased cooling rate of the ingot (Figure 2 and Figure 3). Thus, the increased solubility of Zr and Sc in the supersaturated solid solution due to the increased casting rate is leveled by the growing number of high-angle grain boundaries. In addition, when the cooling rate increases in the Al0.3Mg1Si0.3Sc0.15Zr alloy, the electrical resistance also increases, and other fine particles are almost completely absent (Figure 9, Figure 10 and Figure 11). This suggests that the growth of the high-angle boundaries primarily affects the appearance of the (AlSi)3ScZr-type particles.

4. Conclusions

1. Minor zirconium and scandium additions cause significant grain structure refinement in the Al0.3Mg1Si alloy with a seven-fold reduction in grain size. A coarse dendritic grain structure is observed in the Al0.3Mg1Si alloy at low crystallization rates. In addition to the dendritic structure, fine equiaxed grains are observed in the Al0.3Mg1Si0.3Sc0.15Zr alloy. The increase in the crystallization rate leads to significant grain refinement in both alloys. At the same time, the Al0.3Mg1Si alloy preserves, in general, its dendritic structure at any cooling rate, while in the Al0.3Mg1Si0.3Sc0.15Zr alloy, it is totally replaced by a uniform fine grain structure.
2. An increase in the cooling rate causes a reduction of fine particles in Al0.3Mg1Si formed during ingot cooling after crystallization. So, only an effect of supersaturated solid solution hardening is observed, thus resulting in a decrease of microhardness. However, a further increase of the solidification rate to 30 °C/s leads to the formation of multiple nonequilibrium eutectic intermetallic particles, stimulating a minor increase in microhardness.
3. In the Al0.3Mg1Si0.3Sc0.15Zr alloy, an increase in the cooling rate causes a continuous increase in microhardness as a result of the discontinuous precipitation of (AlSi)3ScZr-type nanoparticles, which are either coherent with the aluminum matrix or semicoherent, or even fan-shaped. The amount of such particles grows with the increasing crystallization rate, as the length of the high-angle boundaries increases, being one of the sources of their formation. Besides, an even larger amount of nonequilibrium intermetallic particles of a eutectic nature is formed in this alloy, with much smaller sizes than in the Al0.3Mg1Si alloy.

Author Contributions

Conceptualization, E.A., S.K., J.H. and V.A.; methodology, E.A. and S.K.; software, E.A.; validation, E.A. and J.H.; formal analysis, E.A., M.L., J.H. and S.S.; investigation, E.A., M.L., J.H., V.A., S.S. and S.K.; resources, V.A. and S.K.; data curation, E.A. and M.L.; writing—original draft preparation, M.L. and S.S.; writing—review and editing, E.A., S.K. and J.H.; visualization, V.A. and M.L.; supervision, E.A.; project administration, S.K. and E.A.; funding acquisition, S.K. All authors have read and agreed to the published version of the manuscript.

Funding

This study is funded by a grant of the Russian Science Foundation, project 21-19-00548, https://rscf.ru/project/21-19-00548/.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Chausov, M.; Pylypenko, A.; Maruschak, P.; Menou, A. Phenomenological Models and Peculiarities of Evaluating Fatigue Life of Aluminum Alloys Subjected to Dynamic Non-Equilibrium Processes. Metals 2021, 11, 1625. [Google Scholar] [CrossRef]
  2. Chausov, M.; Brezinova, J.; Zasimchuk, E.; Maruschak, P.; Khyzhun, O.; Pylypenko, A.; Bazarnik, P.; Brezina, J. Effect of Structure Self-Organization of Aluminum Alloy D16ChATW under Impact-Oscillatory Loading on Its Fatigue Life. J. Mater. Eng. Perform. 2021, 30, 6235–6242. [Google Scholar] [CrossRef]
  3. Alattar, A.L.; Bazhin, V.Y. Al–Cu–B 4 C Composite Materials for the Production of High-Strength Billets. Metallurgist 2020, 5, 566–573. [Google Scholar] [CrossRef]
  4. Kosov, Y.I.; Bazhin, V.Y. Synthesis of an aluminum–erbium master alloy from chloride–fluoride melts. Russ. Metall. 2018, 2, 139–148. [Google Scholar] [CrossRef]
  5. Belov, N.A.; Alabin, A.; Sannikov, A.; Deev, V.B. Primary crystallization in the Al-Fe-Mn-Ni-Si system as applied to casting alloys based on aluminum-nickel eutectic. Russ. J. Non-Ferr. Met. 2014, 55, 356–364. [Google Scholar] [CrossRef]
  6. Deev, V.B.; Selyanin, I.F.; Ponomareva, K.V.; Yudin, A.S.; Tsetsorina, S.A. Fast cooling of aluminum alloys in casting with a gasifying core. Steel Transl. 2014, 44, 253–254. [Google Scholar] [CrossRef]
  7. Du, H.; Zhang, S.; Zhang, B.; Tao, X.; Yao, Z.; Belov, N.; van der Zwaag, S.; Liu, Z. Ca-modified Al–Mg–Sc alloy with high strength at elevated temperatures due to a hierarchical microstructure. J. Mater. Sci. 2021, 56, 16145–16157. [Google Scholar] [CrossRef]
  8. Belov, N.; Akopyan, T.; Korotkova, N.; Murashkin, M.; Timofeev, V.; Fortuna, A. Structure and Properties of Ca and Zr Containing Heat Resistant Wire Aluminum Alloy Manufactured by Electromagnetic Casting. Metals 2021, 11, 236. [Google Scholar] [CrossRef]
  9. Kolobnev, N.I.; Ber, L.B.; Khokhlatova, L.B.; Ryabov, D.K. Structure, properties and application of the Al-Mg-Si-(Cu) system alloys. Metall. Heat Treat. Met. 2011, 9, 40–45. [Google Scholar] [CrossRef]
  10. Hirsch, J. Aluminium in Innovative Light-Weight Car Design. Mater. Trans. 2011, 52, 818–824. [Google Scholar] [CrossRef] [Green Version]
  11. Polmear, I. Light Alloys: From Traditional Alloys to Nanocrystals; Elsevier: Amsterdam, The Netherlands, 2005. [Google Scholar]
  12. Kharakterova, M.L.; Eskin, D.G.; Toropova, L.S. Precipitation hardening in ternary alloys of the Al Sc Cu and Al Sc Si systems. Acta Metall. Mater. 1994, 7, 2285–2290. [Google Scholar] [CrossRef]
  13. Zakharov, V.V. Effect of Scandium on the Structure and Properties of Aluminum Alloys. Met. Sci. Heat Treat. 2003, 45, 246–253. [Google Scholar] [CrossRef]
  14. Mousavi, M.; Cross, C. Effect of scandium and titanium–boron on grain refinement and hot cracking of aluminium alloy 7108. Sci. Technol. Weld. Join. 1999, 4, 381–388. [Google Scholar] [CrossRef]
  15. Kim, J.H.; Kim, J.H.; Yeom, J.T.; Lee, D.G.; Lim, S.G.; Park, N.K. Effect of scandium content on the hot extrusion of Al–Zn–Mg–(Sc) alloy. J. Mater. Process. Technol. 2007, 187, 635–639. [Google Scholar] [CrossRef]
  16. Tsao, C.S.; Chen, C.Y.; Jeng, U.S.; Kuo, T.Y. Precipitation kinetics and transformation of metastable phases in Al–Mg–Si alloys. Acta Mater. 2006, 17, 4621–4631. [Google Scholar] [CrossRef]
  17. Niranjani, V.L.; Kumar, K.H.; Sarma, V.S. Development of high strength Al–Mg–Si AA6061 alloy through cold rolling and ageing. Mater. Sci. Eng. 2009, 515, 169–174. [Google Scholar] [CrossRef]
  18. Lodgaard, L.; Ryum, N. Precipitation of dispersoids containing Mn and/or Cr in Al–Mg–Si alloys. Mater. Sci. Eng. 2000, 283, 144–152. [Google Scholar] [CrossRef]
  19. Esmaeili, S.; Wang, X.; Lloyd, D.J.; Poole, W.J. On the precipitation-hardening behavior of the Al-Mg-Si-Cu alloy AA6111. Metall. Mater. Trans. A 2003, 34, 751–763. [Google Scholar] [CrossRef]
  20. Van Huis, M.; Chen, J.; Sluiter, M.; Zandbergen, H. Phase stability and structural features of matrix-embedded hardening precipitates in Al–Mg–Si alloys in the early stages of evolution. Acta Mater. 2007, 55, 2183–2199. [Google Scholar] [CrossRef]
  21. Marquis, E.; Seidman, D. Nanoscale structural evolution of Al3Sc precipitates in Al (Sc) alloys. Acta Mater. 2001, 49, 1909–1919. [Google Scholar] [CrossRef] [Green Version]
  22. Davydov, V.G.; Rostova, T.D.; Zakharov, V.V.; Filatov, Y.A.; Yelagin, V.I. Scientific principles of making an alloying addition of scandium to aluminium alloys. Mater. Sci. Eng. 2000, 280, 30–36. [Google Scholar] [CrossRef]
  23. Singh, V.; Prasad, K.S.; Gokhale, A.A. Effect of minor Sc additions on structure, age hardening and tensile properties of aluminium alloy AA8090 plate. Scr. Mater. 2004, 50, 903–908. [Google Scholar] [CrossRef]
  24. Yu, K.; Li, W.; Li, S.; Zhao, J. Mechanical properties and microstructure of aluminum alloy 2618 with Al3(Sc, Zr) phases. Mater. Sci. Eng. A 2004, 368, 88–93. [Google Scholar] [CrossRef]
  25. Dev, S.; Stuart, A.A.; Kumaar, R.R.D.; Murty, B.S.; Rao, K.P. Effect of scandium additions on microstructure and mechanical properties of Al–Zn–Mg alloy welds. Mater. Sci. Eng. 2007, 467, 132–138. [Google Scholar] [CrossRef]
  26. Norman, A.; Hyde, K.; Costello, F.; Thompson, S.; Birley, S.; Prangnell, P. Examination of the effect of Sc on 2000 and 7000 series aluminium alloy castings: For improvements in fusion welding. Mater. Sci. Eng. A 2003, 354, 188–198. [Google Scholar] [CrossRef]
  27. Fuller, C.B.; Seidman, D.N.; Dunand, D.C. Creep properties of coarse-grained Al (Sc) alloys at 300 °C. Scr. Mater. 1999, 40, 691–696. [Google Scholar] [CrossRef]
  28. Lee, S.; Utsunomiya, A.; Akamatsu, H.; Neishi, K.; Furukawa, M.; Horita, Z.; Langdon, T. Influence of scandium and zirconium on grain stability and superplastic ductilities in ultrafine-grained Al–Mg alloys. Acta Mater. 2002, 50, 553–564. [Google Scholar] [CrossRef]
  29. Tolley, A.; Radmilovic, V.; Dahmen, U. Segregation in Al3 (Sc, Zr) precipitates in Al–Sc–Zr alloys. Scr. Mater. 2005, 7, 621–625. [Google Scholar] [CrossRef]
  30. Iwamura, S.; Miura, Y. Loss in coherency and coarsening behavior of Al3Sc precipitates. Acta Mater. 2004, 52, 591–600. [Google Scholar] [CrossRef]
  31. Bazhin, V.Y.; Kosov, Y.I.; Lobacheva, O.L.; Dzhevaga, N. Synthesis of aluminum-based scandium–yttrium master alloys. Russ. Metall. (Met.) 2015, 2015, 516–520. [Google Scholar] [CrossRef]
  32. Davydov, V.G.; Elagin, V.I.; Zakharov, V.V.; Rostoval, D. Alloying aluminum alloys with scandium and zirconium additives. Met. Sci. Heat Treat. 1996, 8, 347–352. [Google Scholar] [CrossRef]
  33. Tyvanchuk, A.T.; Yanson, T.I.; Kotur, B.Y.; Zarechnyuk, O.S.; Kharakterova, M.L. Isothermal section of Sc-Al-Si system at 770 K. Izv. Akad. Nauk. SSSR-Met. 1988, 20, 187–188. [Google Scholar]
  34. Rokhlin, L.L.; Bochvar, N.R.; Rybal’Chenko, O.V.; Tarytina, I.E.; Sukhanov, A.V. Phase equilibria in aluminum-rich Al-Sc-Si alloys during solidification. Russ. Metall. (Met.) 2012, 2012, 606–611. [Google Scholar] [CrossRef]
  35. Babaniaris, S.; Ramajayam, M.; Jiang, L.; Langan, T.; Dorin, T. Developing an Optimized Homogenization Process for Sc and Zr Containing Al-Mg-Si Alloys. In Light Metals; Springer: Cham, Switzerland, 2019; pp. 1445–1453. [Google Scholar] [CrossRef] [Green Version]
  36. Babaniaris, S.; Ramajayam, M.; Jiang, L.; Langan, T.; Dorin, T. Tailored precipitation route for the effective utilisation of Sc and Zr in an Al-Mg-Si alloy. Materialia 2020, 10, 100656. [Google Scholar] [CrossRef]
  37. Porter, D.A.; Easterling, K.E. Phase Transformations in Metals and Alloys (Revised Reprint); CRC Press: Boca Raton, FL, USA, 2009. [Google Scholar] [CrossRef]
  38. Wang, F.; Qiu, D.; Liu, Z.; Taylor, J.A.; Easton, M.; Zhang, M.-X. The grain refinement mechanism of cast aluminium by zirconium. Acta Mater. 2013, 61, 5636–5645. [Google Scholar] [CrossRef]
  39. Norman, A.; Prangnell, P.; McEwen, R. The solidification behaviour of dilute aluminium–scandium alloys. Acta Mater. 1998, 46, 5715–5732. [Google Scholar] [CrossRef]
  40. Blake, N.; Hopkins, M.A. Constitution and age hardening of Al-Sc alloys. J. Mater. Sci. 1985, 20, 2861–2867. [Google Scholar] [CrossRef]
  41. Yashin, V.V.; Aryshensky, E.V.; Latushkin, I.A.; Stozharov, D.A. Study of kinetics of the supersaturated solid solution de-composition in alloys of the Al-Mg system with transition elements addition. Tsvetnye Met. 2020, 11, 77–84. [Google Scholar]
Metals 11 02056 g001 550
Figure 1. Temperature depending on time for different chill molds.
Figure 1. Temperature depending on time for different chill molds.
Metals 11 02056 g001
Metals 11 02056 g002a 550Metals 11 02056 g002b 550
Figure 2. Optical microstructure Al0.3Mg1Si—(a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section; Al0.3Mg1Si0.3Sc0.15Zr–(d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Figure 2. Optical microstructure Al0.3Mg1Si—(a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section; Al0.3Mg1Si0.3Sc0.15Zr–(d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Metals 11 02056 g002aMetals 11 02056 g002b
Metals 11 02056 g003 550
Figure 3. Grain size of alloys depending on the cooling rate.
Figure 3. Grain size of alloys depending on the cooling rate.
Metals 11 02056 g003
Metals 11 02056 g004 550
Figure 4. Electrical conductivity of alloys depending on the cooling rate.
Figure 4. Electrical conductivity of alloys depending on the cooling rate.
Metals 11 02056 g004
Metals 11 02056 g005 550
Figure 5. Microhardness of alloys depending on the cooling rate.
Figure 5. Microhardness of alloys depending on the cooling rate.
Metals 11 02056 g005
Metals 11 02056 g006 550
Figure 6. Micrographs of Al0.3Mg1Si alloy. Phases: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Intermetallic compounds: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Figure 6. Micrographs of Al0.3Mg1Si alloy. Phases: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Intermetallic compounds: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Metals 11 02056 g006
Metals 11 02056 g007 550
Figure 7. Micrograph of Al0.3Mg1Si0.3Sc0.15Zr alloy. Phases: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Intermetallic compounds: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Figure 7. Micrograph of Al0.3Mg1Si0.3Sc0.15Zr alloy. Phases: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Intermetallic compounds: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Metals 11 02056 g007
Metals 11 02056 g008 550
Figure 8. Number and size of dispersoids in alloys. Al0.3Mg1Si: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Al 0.3Mg1Si0.3Sc0.15Zr: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Figure 8. Number and size of dispersoids in alloys. Al0.3Mg1Si: (a) steel chill mold; (b) copper chill mold; (c) copper chill mold of round section. Al 0.3Mg1Si0.3Sc0.15Zr: (d) steel chill mold; (e) copper chill mold; (f) copper chill mold of round section.
Metals 11 02056 g008
Metals 11 02056 g009 550
Figure 9. Al0.3Mg1Si0.15Zr0.3S steel chill mold (a); (b) Particles (AlSi)3ScZr and Al3Sc; (c) EDS profile line scan.
Figure 9. Al0.3Mg1Si0.15Zr0.3S steel chill mold (a); (b) Particles (AlSi)3ScZr and Al3Sc; (c) EDS profile line scan.
Metals 11 02056 g009
Metals 11 02056 g010 550
Figure 10. Al0.3Mg1Si0.15Zr0.3S copper chill mold (a); (b) Particles (AlSi)3ScZr; (c) EDS profile line scan.
Figure 10. Al0.3Mg1Si0.15Zr0.3S copper chill mold (a); (b) Particles (AlSi)3ScZr; (c) EDS profile line scan.
Metals 11 02056 g010
Metals 11 02056 g011 550
Figure 11. Al0.3Mg1Si0.15Zr0.3S copper cone (a) Al3Sc particles, bright field; (b) Al3Sc particles, dark field in the superstructural reflection; (c) Al3Sc particles with zirconium, bright field; (d) EDS profile line scan.
Figure 11. Al0.3Mg1Si0.15Zr0.3S copper cone (a) Al3Sc particles, bright field; (b) Al3Sc particles, dark field in the superstructural reflection; (c) Al3Sc particles with zirconium, bright field; (d) EDS profile line scan.
Metals 11 02056 g011
Table
Table 1. Alloys and method of casting samples.
Table 1. Alloys and method of casting samples.
AlloySteel Chill MoldCopper Chill MoldConical Chill Mold
Al0.3Mg1Si+++
Al0.3Mg1Si0.3Sc0.15Zr+++
Table
Table 2. Metal average cooling rates.
Table 2. Metal average cooling rates.
Type of the Casting MoldCooling Rate, °C/s
during Crystallizationafter Crystallization Until Complete CoolingAll-Time Average
Steel chill mold20.70.72
Copper chill mold103.23.5
Copper chill mold with circular section308.18.6
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Aryshenskii, E.; Lapshov, M.; Konovalov, S.; Hirsch, J.; Aryshenskii, V.; Sbitneva, S. The Casting Rate Impact on the Microstructure in Al–Mg–Si Alloy with Silicon Excess and Small Zr, Sc Additives. Metals 2021, 11, 2056. https://doi.org/10.3390/met11122056

AMA Style

Aryshenskii E, Lapshov M, Konovalov S, Hirsch J, Aryshenskii V, Sbitneva S. The Casting Rate Impact on the Microstructure in Al–Mg–Si Alloy with Silicon Excess and Small Zr, Sc Additives. Metals. 2021; 11(12):2056. https://doi.org/10.3390/met11122056

Chicago/Turabian Style

Aryshenskii, Evgenii, Maksim Lapshov, Sergey Konovalov, Jurgen Hirsch, Vladimir Aryshenskii, and Svetlana Sbitneva. 2021. "The Casting Rate Impact on the Microstructure in Al–Mg–Si Alloy with Silicon Excess and Small Zr, Sc Additives" Metals 11, no. 12: 2056. https://doi.org/10.3390/met11122056

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop