Applications of Rare Earth Metals in Al-Si Cast Alloys

The present article reviews a large number of research publications on the effect of mischmetal (MM), rare earth metals (RE), La or Ce, and combinations of La + Ce on the performance of Al-Si cast alloys mainly 319, 356, 380, 413, and 390 alloys. Most of these articles focused on the use of rare earth metals as a substitute for strontium (Sr) as a eutectic silicon (Si) modifier if added in low percentage (< 1 wt.%) to avoid precipitation of a significant amount of insoluble intermetallics and hence poor mechanical properties. Other points that were considered were the affinity of RE to react with Sr., reducing its effectiveness as modifier, as well as the grain refining efficiency of the added RE in any form. None of these articles mentioned the exact composition of the RE used and percentage of tramp elements inherited from the parent ore. Using high purity La or Ce proved to have no effect on the Si shape, size or distribution, in particular at low solidification rates (thick sections). However, regardless the source of the RE, its addition to Sr-modified alloys reduced the modification effect. As for grain refining, apparently a high percentage of RE (> 1 wt.%) is required to achieve a noticeable reduction in grain size, however at the cost of alloy brittleness.

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Effect of Ca Concentration on Microstructure and Mechanical Properties of As-Cast and As-Extruded Quasicrystal-Strengthened Mg-7.2Zn-2.4Gd Alloy

Advances in Materials Science and Engineering ◽

10.1155/2018/9138753 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

Jianchun Sun ◽

Yilong Ma ◽

Hongwei Miao ◽

Kejian Li ◽

Chunhong Li ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Property ◽

Grain Size ◽

Rare Earth ◽

Room Temperature ◽

Earth Element ◽

Extrusion Ratio ◽

Gravity Casting ◽

Ca Addition ◽

Cast Alloys

Quasicrystal-strengthened Mg-Zn-RE (RE = rare-earth element) alloys have been investigated extensively due to their excellent mechanical properties. Here, we prepare quasicrystal-strengthened Mg-7.2Zn-2.4Gd (wt.%) alloy with different concentrations of Ca addition (0, 0.16, 0.32, and 0.64 wt.%) by traditional gravity casting, followed by extrusion at 573 K with the extrusion ratio of 9 : 1. The microstructure and room temperature tensile properties of as-cast and as-extruded alloys are characterized. With the addition of the trace amount of Ca, the I-phase tends to transfer into W-phase due to the appearance of Mg2Ca and Mg6Zn3Ca2. As a consequence, the mechanical properties of the as-cast Ca containing alloys are downgraded. After extrusion, in comparison to the as-cast alloys, microstructure of the four types of alloys is refined and mechanical property is enhanced greatly. With the increasing of Ca concentration, the grain size is decreased gradually. However, the yield strength of the alloys is decreased to about 230 MPa and then up to 269 MPa, while the elongation increases first from 12.9% to 13.6% yet then decreases to 9.9%.

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The Effect of Alloying on the Fractional Composition, Shape and Grain Size Distribution of the Structure Alloy GAP the Fe-Nd-B System

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.841.214 ◽

2020 ◽

Vol 841 ◽

pp. 214-219

Author(s):

Victoriia A. Chaika ◽

V.V. Savin ◽

Mikhail Sorokovikov ◽

Artem Marikhin

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Rare Earth ◽

Grain Growth ◽

Grain Shape ◽

Fractional Composition ◽

Rare Earth Metals ◽

Grain Structure ◽

Gas Atomization ◽

Radial Gradient

The magnetic and mechanical properties of the magnets Fe-Nd-B system are more dependent on the size and shape of the grain structure. The authors explored the effect of the neodymium content and the addition of transition metals (Mo, Co, Al) and rare-earth metals (Dy, Tb) on the formation of the structure alloy gas atomization powder the Fe-Nd-B system. It has been shown that doping enhances the formation of grain blocks with a radial gradient in the direction of grain growth. The alloying of a gas atomization powder alloy of the Fe-Nd-B system with rare-earth metals increases the anisotropy of the grain shape.

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Magnetic and Electronic Properties of Heavy Lanthanides (Gd, Tb, Dy, Er, Ho, Tm)

Crystals ◽

10.3390/cryst11020082 ◽

2021 ◽

Vol 11 (2) ◽

pp. 82

Author(s):

Radel R. Gimaev ◽

Aleksei S. Komlev ◽

Andrei S. Davydov ◽

Boris B. Kovalev ◽

Vladimir I. Zverev

Keyword(s):

Rare Earth ◽

Electronic Properties ◽

High Purity ◽

Materials Science ◽

Rapid Development ◽

Rare Earth Metals ◽

State University ◽

Important Place ◽

Heavy Lanthanides ◽

Baikov Institute

Rare earth metals (REM) occupy a special and important place in our lives. This became especially noticeable during the rapid development of industry in the industrial era of the twentieth century. The tendency of development of the rare-earth metals market certainly remains in the XXI century. According to experts estimates the industry demand for chemical compounds based on them will tend to grow during the nearest years until it reaches the market balance. At the same time, the practical use of high-purity rare-earth metals requires the most accurate understanding of the physical properties of metals, especially magnetic ones. Despite a certain decline in interest in the study of high-purity REM single crystals during the last decade, a number of scientific groups (Ames Lab, Lomonosov Moscow State University (MSU), Baikov Institute of Metallurgy and Materials Science Russian Academy of Science (RAS)) are still conducting high-purity studies on high-purity metal samples. The present article is a combination of a review work covering the analysis of the main works devoted to the study of heavy REMs from gadolinium to thulium, as well as original results obtained at MSU. The paper considers the electronic properties of metals in terms of calculating the density of states, analyzes the regularities of the magnetic phase diagrams of metals, gives the original dependences of the Neel temperature and tricritical temperatures for Gd, Tb, Dy, Er, Ho, Tm, and also introduces a phenomenological parameter that would serve as an indicator of the phase transformation in heavy REMs.

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Novel grain refinement of AZ91E magnesium alloy and the effect on hot tearing during solidfication

10.32920/ryerson.14649522.v1 ◽

2021 ◽

Author(s):

Abdallah Elsayed

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Magnesium Alloy ◽

Grain Refinement ◽

Magnesium Alloys ◽

Hot Tearing ◽

Grain Refining ◽

Grain Refiner ◽

Structural Applications ◽

Hot Tearing Susceptibility

For the A1-5Ti-1B grain refiner, the addition of 0.1 wt.% provided a 68 % reduction in grain size as compared to the unrefined AZ91E alloy at a holding time of five minutes. Grain growth restriction by TiB₂ particles was the source of grain refinement. With the addition of A1-5Ti-1B, only a small reduction in hot tearing susceptibility ws observed because large TiA1₃ particles bonded poorly with the eutectic and blocked feeding channels.The addition of 1.0 wt.% A1-1Ti-3B provided a grain size reduction of 63% as compared to the unrefined AZ91E alloy at a holding time of five minutes. The grain refinement with A1-1Ti-3B addition was attributed to a combination of TiB₂ grain growth restriction and A1B₂ nucleating sites. A significant reduction in hot tearing susceptibility was observed with A1-1Ti-3B addition as a result of a higher cooling rate and shorter local soldification time as compared to the AZ91E alloy. The reduction in hot tearing susceptibility was attributed to the good interface between eutectic and TiB₂ particles. Both grain refiners demonstrated a good resistance to fading during the holding times investigated. In addition, the AZ91E + A1-5Ti-1B and AZ91E + A1-1Ti-3B castings showed much fewer dislocation networks as compared to the untreated AZ91E casting.The development of efficient A1-Ti-B refiners can also improve castability of magnesium alloys. In addition, the fade resistant A1-Ti-B grain refiners can reduce operating costs and maintain productivity on the foundry floor. Thus, magnesium alloy with A1-Ti-B treatment have the potential for more demanding structural applications in the automobile and aerospace industries. Vehicle weight in the aerospace and automotive industries directly impacts carbon emissions and fuel efficiency. An increase in the use of lightweight materials for structural applications will result in lighter vehicles. Low density materials, such as magnesium (1.74 g/cm³) are a potential alternative to aluminium (2.70 g/cm³), to reduce component weight in structural applications.However, current magnesium alloys still do not have adequate mechanical properties and castability to meet the performance specifications of the automotive and aerospace industries. Grain refinement can significantly improve mechanical properties and reduce hot tearing during permanent mould casting. Recently, Al-Ti-B based grain refiners have shown potential in grain refining magnesium-aluminum alloys such as AZ91E. This study investigates the grain refining efficiency and fading of A1-5Ti-1B and A1-1Ti-3B in AZ91E magnesium alloy and their subsequent effect on hot tearing.The grain refiners were added at 0.1, 0.2, 0.5 and 1.0 wt.% levels. For the grain refinement and fading experiments, the castings were prepared using graphite moulds with holding times of 5, 10 and 20 minutes. For the hot tearing experiments, castings were produced representing the optimal addition level of each grain refiner. The castings were prepared using a permanent mould with pouring and mould temperatures of 720 and 180 ºC, respectively. The castings were characterized using SEM, TEM, optical microscopy and thermal analysis.

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Research Progress in Preparation and Purification of Rare Earth Metals

Metals ◽

10.3390/met10101376 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1376

Author(s):

Hang Liu ◽

Yao Zhang ◽

Yikun Luan ◽

Huimin Yu ◽

Dianzhong Li

Keyword(s):

Rare Earth ◽

High Purity ◽

Rare Earth Metals ◽

Melting Zone ◽

Thermal Reduction ◽

Zone Melting ◽

Research Progress ◽

Molten Salt Electrolysis ◽

Interstitial Impurities ◽

Metallic Impurities

The purity of rare earth metals is one of the most important factors to research and develop high technique materials. However, high purity rare earth metals are not easily achieved. This review summarizes the preparation and purification methods of rare earth metals. First, the preparation principle and process of molten salt electrolysis and metal thermal reduction are introduced. The main sources of metallic impurities and interstitial impurities in rare earth metals as well as the action mechanism of reducing the concentration of different impurities are analyzed and summarized. Then, the purification principle and process of vacuum distillation, arc melting, zone melting, and solid state electromigration are also discussed. Furthermore, the removal effect and function rule of metallic impurities and interstitial impurities in rare earth metals are outlined. Finally, the crucial issues in the development of high purity rare earth metals are put forward, and the development direction of high purity rare earth metals in future are pointed out on this basis.

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Effect of Rare Earth Metals on the Mechanical Properties and Fractography of Al–Si-Based Alloys

International Journal of Metalcasting ◽

10.1007/s40962-019-00336-x ◽

2019 ◽

Vol 14 (1) ◽

pp. 108-124 ◽

Cited By ~ 4

Author(s):

M. F. Ibrahim ◽

M. H. Abdelaziz ◽

A. M. Samuel ◽

H. W. Doty ◽

F. H. Samuel

Keyword(s):

Mechanical Properties ◽

Rare Earth ◽

Rare Earth Metals

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The Influence Of The Rare Earth Metals Modification On The Fracture Toughness Of G17CrMo5-5 Cast Steel At Low Temperatures

Archives of Metallurgy and Materials ◽

10.1515/amm-2015-0205 ◽

2015 ◽

Vol 60 (2) ◽

pp. 773-777 ◽

Cited By ~ 1

Author(s):

I. Dzioba ◽

J. Kasińska ◽

R. Pała

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Rare Earth ◽

Low Temperatures ◽

Cast Steel ◽

Rare Earth Metals ◽

Positive Influence ◽

Reference Temperature ◽

Brittle To Ductile Transition ◽

The Rare Earth

Abstract This paper presents the influence of the rare earth metals (REM) modification on mechanical properties and fracture toughness of G17CrMo5-5 cast steel at low temperatures. The REM was in the form of mishmetal. The research has been performed on serial (several) industrial melts. The fracture toughness values of unmodified and modified cast steel at the temperature range from −80°C to 20°C were tested. The reference temperatures of the brittle-to-ductile transition, TQ, for both unmodified and modified cast steel were determined. The positive influence of the modification by REM on the fracture toughness and the reference temperature TQ are shown.

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