scholarly journals Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Emad M. Elgallad ◽  
Herbert W. Doty ◽  
Saleh A. Alkahtani ◽  
Fawzy H. Samuel
Keyword(s):  
Rare Earth ◽  
Standard Deviation ◽  
Melting Temperature ◽  
Eutectic Temperature ◽  
Rare Earth Metals ◽  
Rare Earth Intermetallics ◽  
High Affinity ◽  
Eutectic Si ◽  
Microstructural Examination

This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium) on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13)% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
M. G. Mahmoud ◽  
A. M. Samuel ◽  
H. W. Doty ◽  
S. Valtierra ◽  
F. H. Samuel
Keyword(s):  
Rare Earth ◽  
Eutectic Temperature ◽  
Rare Earth Metals ◽  
Microstructural Characterization ◽  
Second Phase ◽  
White Phase ◽  
Eutectic Si ◽  
Ti Addition ◽  
Grey Phase

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 μm 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.

scholarly journals Influence of Compound Deoxidation of Steel with Al, Zr, Rare Earth Metals, and Ti on Properties of Heavy Castings

2012 ◽  
Vol 12 (1) ◽  
pp. 99-104 ◽  
Author(s):  
J. Senberger ◽  
J. Cech ◽  
A. Zadera
Keyword(s):  
Rare Earth ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Rare Earth Metals ◽  
High Affinity ◽  
Nitrogen Activity ◽  
Steel Castings ◽  
Heavy Castings ◽  
Nitrogen Contents ◽  
High Aluminium

Influence of Compound Deoxidation of Steel with Al, Zr, Rare Earth Metals, and Ti on Properties of Heavy Castings Heavy steel castings deoxidized with aluminium are sometimes brittle intercrystalline failed during their service along primary grain boundaries what is initiated by aluminium nitrides and so called conchoidal fractures are formed. The tendency to forming the conchoidal fractures depends in particular on cooling rate (the casting modulus), aluminium and nitrogen contents in steel. During deoxidation, when manufacturing heavy castings, the elements with high affinity to nitrogen, zirconium or titanium, are added to steel that would decrease nitrogen activity by the bond on stable nitrides. The formation of stable nitrides should reduce the tendency of steel to the formation of conchoidal fractures. Deoxidation was thermodynamically analyzed at presence of the mentioned elements. For particular conditions a probable course of deoxidation was estimated at test castings. The deoxidation course was checked by microanalysis of deoxidation products (inclusions). For service and experimental castings the anticipated composition of inclusions was compared. It has been proved that in heavy castings with high aluminium contents in steel under studied conditions neither the addition of zirconium nor of titanium nor of rare earth metals will prevent the formation of conchoidal fractures.

Magnetic susceptibility of liquid heavy rare earth metals

1979 ◽  
Vol 40 (C5) ◽  
pp. C5-260-C5-261 ◽  
Author(s):  
M. Müller ◽  
E. Huber ◽  
H.-J. Güntherodt
Keyword(s):  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Rare Earth Metals ◽  
Heavy Rare Earth

ELECTRONIC RELAXATION IN RARE EARTH METALS AND ALLOYS - A NON-KRAMERS EXAMPLE : Tm3+

1980 ◽  
Vol 41 (C1) ◽  
pp. C1-25-C1-31 ◽  
Author(s):  
N. S. Dixon ◽  
L. S. Fritz ◽  
Y. Mahmud ◽  
B. B. Triplett ◽  
S. S. Hanna ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals ◽  
Metals And Alloys ◽  
Electronic Relaxation

Leaching of Rare Earth Metals from Manganese Nodule by HCl Solution

2015 ◽  
Vol 53 (9) ◽  
pp. 637-641
Author(s):  
Chul-Woo Nam ◽  
Kyung-Ho Park ◽  
Hyun-Ho Kim ◽  
Jin-Tae Park
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals ◽  
Manganese Nodule ◽  
Hcl Solution

Physico-chemical properties of the rare-earth metals, scandium, and yttrium

1963 ◽  
Vol 79 (2) ◽  
pp. 263-293 ◽  
Author(s):  
E.M. Savitskii ◽  
V.F. Terekhova ◽  
O.P. Naumkin
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals ◽  
Chemical Properties ◽  
Physico Chemical ◽  
The Rare Earth

Ferromagnetism and antiferromagnetism of rare-earth metals

1964 ◽  
Vol 82 (3) ◽  
pp. 449-498 ◽  
Author(s):  
Konstantin P. Belov ◽  
R.Z. Levitin ◽  
S.A. Nikitin
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals

Dc arc emission analysis of rare earth metals and their oxides with sorption preconcentration of impurities

2018 ◽  
Vol 84 (11) ◽  
pp. 9-14
Author(s):  
E. S. Koshel ◽  
V. B. Baranovskaya ◽  
M. S. Doronina
Keyword(s):  
Rare Earth ◽  
Rare Earth Metals ◽  
Analytical Signal ◽  
Graphite Powder ◽  
Atomic Emission ◽  
Standard Samples ◽  
Emission Analysis ◽  
Sorption Preconcentration ◽  
Sample Shape

The analytical capabilities of arc atomic emission determination of As, Bi, Sb, Cu, Te in rare earth metals (REM) and their oxides after preparatory group concentration using S,N-containing heterochain polymer sorbent are studied on a high-resolution spectrometer “Grand- Extra” (“WMC-Optoelectron-ics” company, Russia). Sorption kinetics and dependence of the degree of the impurity extraction on the solution acidity are analyzed to specify conditions of sorption concentration. To optimize the procedure of arc atomic emission determination of As, Bi, Sb, Cu, and Te various schemes of their sorption preconcentration and subsequent processing of the resulted concentrate with the addition of a collector at different stages of the sorption process have been considered. Graphite powder is used as a collector in analysis of rare earth oxides due to universality and relative simplicity of the emission spectrum. Conditions of analysis and parameters of the spectrometer that affect the analytical signal (mass and composition of the sample, shape and size of the electrodes, current intensity and generator operation mode, interelectrode spacing, wavelengths of the analytical lines) are chosen. The evaporation curves of the determinable impurities were studied and the exposure time of As, Bi, Sb, Cu, and Te in the resulted sorption concentrate was determined. Correctness of the obtained results was evaluated using standard samples of the composition and in comparisons between methods. The results of the study are used to develop a method of arc chemical-atomic emission analysis of yttrium, gadolinium, neodymium, europium, scandium and their oxides in a concentration range of n x (10-2 - 10-5) wt.%.

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