Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

Alkahtani, Saleh A.; Elgallad, E. M.; Tash, Mahmoud M.; Samuel, A. M.; Samuel, F. H.

doi:10.3390/ma9010045

Cited by 46 publications

(18 citation statements)

References 19 publications

(32 reference statements)

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“…Figures 3 and 4 demonstrate the e ect of adding a relatively large amount of RE metals (without or with 0.15%Ti) to both base alloys. Based on these gures, it is clear that these additions resulted in As reported previously by the present authors [3,17], the observed depression in the eutectic temperature due to addition of RE metals is not necessarily related to modi cation of the eutectic Si particles as shown in Figure 5. It should be mentioned that only La revealed partial modi cation but was not as e ective a modi er as Sr in the Sr-treated alloys.…”

Section: Resultssupporting

confidence: 83%

Rare Earth Metal‐Based Intermetallics Formation in Al–Cu–Mg and Al–Si–Cu–Mg Alloys: A Metallographic Study

Samuel

Elgallad

Mahmoud

et al. 2018

Advances in Materials Science and Engineering

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This study was conducted on Al–Cu–Mg and Al–Si–Cu–Mg alloys containing either 5%La or 5%Ce. Two levels of Ti addition were examined, i.e., 0.05% and 0.15%. Thermal analysis was the only technique used to obtain castings, from which samples were then sectioned for metallographic examination. Based on the results obtained, the following points may be highlighted. Addition of a fairly large amount of RE metals (La or Ce) leads to the appearance of several peaks in the solidification curve between the precipitation of the primary α-Al phase and the (Al–Al2Cu) eutectic reaction. Although a significant drop in the eutectic temperature is caused by the addition of 5%La or Ce, the corresponding modification of the eutectic Si is marginal. Two main types of intermetallics were documented: a gray phase in the form of sludge with a fixed composition and a white phase in the shape of thin platelets. Due to the high affinity of RE to react with Si, Fe, and Cu, several compositions were obtained explaining the observed multiple peaks in the solidification curve. Judging by the morphology of the gray phase, it is assumed that this phase is precipitated in the liquid state and acts as a nucleation site for the white phase. Lanthanum and Ce can substitute each other.

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Section: Resultssupporting

confidence: 83%

Rare Earth Metal‐Based Intermetallics Formation in Al–Cu–Mg and Al–Si–Cu–Mg Alloys: A Metallographic Study

Samuel

Elgallad

Mahmoud

et al. 2018

Advances in Materials Science and Engineering

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“…RE-treated alloys can maintain the modified structure much longer than Na-treated alloys. A reliable and persistent eutectic modification effect can be obtained with rare earth addition [2][3][4][5][6]. However, the minimum amount of rare earths necessary to obtain proper modification is exceptionally large.…”

Section: Introductionmentioning

confidence: 99%

Effect of Rare Earth Metals, Sr, and Ti Addition on the Microstructural Characterization of A413.1 Alloy

Mahmoud

Samuel

Doty

et al. 2017

Advances in Materials Science and Engineering

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The present work was performed on A413.1 alloy containing 0.2-1.5 wt% rare earth metals (lanthanum or cerium), 0.05-0.15% Ti, and 0-0.02 wt% Sr. These elements were either added individually or combined. Thermal analysis, image analysis, and electron probe microanalysis were the main techniques employed in the present study. The results show that the use of the depression in the eutectic temperature as a function of alloy modification cannot be applied in the case when the alloy is treated with rare earth metals. Increasing the concentration of RE increases the solidification zone especially in Sr-modified alloys leading to poor feeding ability. This observation is more prominent in the case of Ce addition. Depending upon the amount of added Ti, two RE based intermetallics can be formed: (i) a white phase, mainly platelet-like (approximately 2.5 m thick), that is rich in RE, Si, Cu, and Al and (ii) a second phase made up of mainly grey sludge particles (star-like) branching in different directions. The grey phase is rich in Ti with some RE (almost 20% of that in the white phase) with traces of Si and Cu. There is a strong interaction between RE and Sr leading to a reduction in the efficiency of Sr as a eutectic Si modifier causing particle demodification.

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“…There are examples with an application of mischmetal and individual elements with positive effects, no effects [89], and detrimental influence on properties of aluminum alloys [90]. Rare earth elements such as La, Ce, Nd, and Y were tested with the Al−Si matrix [91]; Er with Al−Mg, Al−Zn−Mg, Al−Zn−Mg−Cu, Al−Li, and Al−Cu grades [92]; or Sm with Al−Si−Cu grades [93]. Among rare earths, cerium and scandium are of particular interest for aluminum alloying, as emphasized in [94][95][96].…”

Section: Rare Earth Metals In Aluminum Alloysmentioning

confidence: 99%

Thermal Stability of Aluminum Alloys

Czerwiński

2020

Materials

123

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Thermal stability, determining the material ability of retaining its properties at required temperatures over extended service time, is becoming the next frontier for aluminum alloys. Its improvement would substantially expand their range of structural applications, especially in automotive and aerospace industries. This report explains the fundamentals of thermal stability; definitions, the properties involved; and the deterioration indicators during thermal/thermomechanical exposures, including an impact of accidental fire, and testing techniques. For individual classes of alloys, efforts aimed at identifying factors stabilizing their microstructure at service temperatures are described. Particular attention is paid to attempts of increasing the current upper service limit of high-temperature grades. In addition to alloying aluminum with a variety of elements to create the thermally stable microstructure, in particular, transition and rare-earth metals, parallel efforts are explored through applying novel routes of alloy processing, such as rapid solidification, powder metallurgy and additive manufacturing, engineering alloys in a liquid state prior to casting, and post-casting treatments. The goal is to overcome the present barriers and to develop novel aluminum alloys with superior properties that are stable across the temperature and time space, required by modern designs.

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Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

Cited by 46 publications

References 19 publications

Rare Earth Metal‐Based Intermetallics Formation in Al–Cu–Mg and Al–Si–Cu–Mg Alloys: A Metallographic Study

Rare Earth Metal‐Based Intermetallics Formation in Al–Cu–Mg and Al–Si–Cu–Mg Alloys: A Metallographic Study

Effect of Rare Earth Metals, Sr, and Ti Addition on the Microstructural Characterization of A413.1 Alloy

Thermal Stability of Aluminum Alloys

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