The article presents the design guidelines and technical implementation of an experimental stand for melting and casting in controlled protective atmosphere the ultralight magnesium-lithium alloys, including also a small furnace for the heat treatment of such alloys. The manufacture and implementation of these devices provides a basis for studies on the preparation of ultra-light alloys for further plastic working

A. Białobrzeski

K. Saja

Abstract The article presents the design guidelines and technical implementation of an experimental stand for melting and casting in controlled protective atmosphere the ultralight magnesium-lithium alloys, including also a small furnace for the heat treatment of such alloys. The manufacture and implementation of these devices provides a basis for studies on the preparation of ultra-light alloys for further plastic working

A Białobrzeski

K Saja

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A R C H I V E S  
o f  
F O U N D R Y  E N G I N E E R I N G  
 
 
 
Published quarterly as the organ of the Foundry Commission of the Polish Academy of Sciences 
ISSN (1897-3310) 
Volume 11 
Issue 3/2011 
 
17 – 20 
 
3/3 
 
 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 1 ,  I s s u e  3 / 2 0 1 1 ,  1 7 - 2 0  17 
 
Experimental stand for melting and casting 
of ultralight Mg-Li alloys 
 
A. Białobrzeski
a,b
, K. Saja
a 
a
Foundry Research Institute, Zakopiańska 73, 30-418 Kraków, Poland 
b
University of Bielsko-Biała, Willowa 2, 43-309 Bielsko-Biała, Poland 
 
Received 01-04-2011; accepted in revised form 04-04-2011 
 
 
Abstract 
 
The article presents the design guidelines and technical implementation of an experimental stand for melting and casting in controlled 
protective atmosphere the ultralight magnesium-lithium alloys, including also a small furnace for the heat treatment of such alloys. The 
manufacture and implementation of these devices provides a basis for studies on the preparation of ultra-light alloys for further plastic 
working. 
 
Keywords: Mg-Li Alloys, Furnaces For Melting And Casting Of Ultralight Alloys, Protective Atmosphere  
 
 
1. Introduction 
 
Traditional magnesium alloys belong to a group of light 
alloys, while magnesium alloys with lithium are known as 
ultralight alloys. Their specific gravity at the maximum currently 
used lithium content (14 -16at.%) is 1,35-1,45 g/cm
3
, which is not 
much more than the density of water (  1.0 g/cm
3
). 
Great technical importance has the family of magnesium 
alloys with aluminium, zinc and manganese, where Al and Zn 
increase the alloy strength, and Mn improves the anticorrosive 
behaviour. The alloying additions that increase the resistance to 
high temperatures and improve plastic properties as well as 
oxidation resistance are: beryllium, calcium, cerium, cadmium, 
and titanium. Iron, silicon and nickel deteriorate the mechanical 
properties of alloys and their corrosion resistance. Magnesium 
alloys are characterised by a beneficial strength and/or elastic 
modulus-to-density ratio, which makes them capable of carrying 
static and dynamic loads similar to iron and aluminium alloys, 
while offering – additionally – good damping properties. 
They are resistant to corrosion (providing iron, nickel and 
copper contaminations are effectively reduced), and are resistant 
to changing mechanical loads, also under the conditions of 
elevated temperatures. Besides standard and well-known alloys 
based on Mg-Al-Zn and Mg-Al-Mn systems, used primarily in die 
casting technology, other alloys are also available, including high 
creep resistance family of alloys with fine-grained structure and 
an addition of zirconium, designed for casting in ceramic moulds 
and processing by other methods. 
Magnesium alloys are used in construction of engine blocks, 
heads, gearbox housings, suspension components, steering parts, 
seats, body parts and other car accessories. These alloys are also 
used in the construction of motorcycles, in bicycles, sports 
facilities, and recreational facilities, in the production of 
household appliances, etc. Magnesium alloys are successfully 
used in the aerospace industry (construction of helicopter and 
airframe components) and in electronic equipment (laptop cases, 
mobile phone parts due to, among others. the ability of 
magnesium to absorb and scatter the electromagnetic radiation), 
in nuclear reactors, e.g. for neutron-absorbing guards.  
Magnesium alloy castings are by about 20-30% lighter than cast 
aluminium alloys and by 50-75% lighter than iron castings. Cast 
elements are mainly made by the die casting technology 
(approximately 90%). 
Studies of Mg alloys mainly aim at finding alternative 
elements forming intermetallic phases, such as calcium, 
scandium, or gadolinium, which enhance the strength of alloy at 
high temperatures. Particular attention should be paid to alloys 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 1 ,  I s s u e  3 / 2 0 1 1 ,  1 7 - 2 0  18 
with the addition of rare earth metals, and with the addition of 
yttrium and silver. For special applications in aerospace and 
sports cars, for short periods of time, they can withstand 
temperatures up to 300°C [2] offering, besides good resistance to 
high temperature, also stiffness and abrasion wear resistance. 
Newly developed composite materials based on Mg alloy, 
reinforced with fibres and particles, open the way for other uses in 
parts operating under the conditions of high and changing loads. 
Some attention also deserve the amorphous materials based on 
magnesium, still at the initial stage of basic research. Widening 
the scope of research on the properties of these materials is in 
close connection with the development of advanced innovative 
technological processes. In addition to improvements introduced 
to the processes already existing and used (pressure die casting, 
gravity die casting, etc.), new casting technologies are developed, 
such as semi-solid metal casting, squeeze casting, etc.   
Current development trends in the rapid solidification process, in 
the spray casting process, and spraying of dispersed inert particles 
with a reactive in situ introduction of alloying elements, offer 
further opportunities for the manufacture of special magnesium 
alloys. In addition, metallic foams are a new generation of 
materials for ultra-lightweight structural components. 
Another use of magnesium is in metallurgical processes such as 
spheroidising treatment of cast iron and deoxidation of metal bath.     
First attempts to use lithium as a component of metal alloys were 
taken during the First World War. During that period, the German 
industry has suffered from a shortage of tin, which is necessary 
for the production of bearings. Lead alloy with lithium - 
developed by Jan Czochralski – has turned out to be an excellent 
bearing metal, used mainly for the wheels of railway cars, and 
hence its name "Bahnmetal”. 
In recent years, a marked increase of interest in the 
magnesium and lithium alloys with additions of Al, Cd, Zn and 
Ag of reduced density has been observed. It is assumed that 
1wt.% of lithium reduces the density of magnesium alloys by 
about 3%.  
Figure 1 shows the phase equilibrium diagram of Mg-Li alloys 
and the expected change in alloy density with the changing 
lithium content. 
The solubility of lithium in magnesium characterised by a 
hexagonal structure is very low and amounts to about 5 wt%, 
while magnesium forms a wide range of  solid solutions by 
dissolving in lithium of the body-centred cubic structure up to 
90wt.%. Lithium is beneficial for the formability of magnesium 
alloys by replacing the hardly deformable hexagonal lattice of -
Mg (hcp) with a regular body centred cubic -Li (bcc) lattice, 
though the latter one tends to reduce the mechanical properties 
due to the appearance of  phase. An optimum combination of 
mechanical properties of alloys occurs in binary +  alloys 
containing lithium in the range of 6-11wt.%. 
 
 
 
 
 
 
Fig. 1. Phase equilibrium diagram of Mg-Li alloys and change in 
alloy density with lithium content changing in a binary Mg-Li 
alloy according to [1] 
Gęstość – density 
Temperatura – temperature 
 
Figure 1 also shows the expected change in the density of Mg-Li 
alloy depending on its chemical composition (lithium content). 
The chart shows that it is even possible to obtain an alloy with a 
density of less than 1 g/cm3. Alloys with lithium content 
comprised in this range are estimated to have in as-cast condition 
the elongation of up to several dozen percent. An addition of 
aluminium to Mg-Li alloys [16] leads to the appearance of a 
hexagonal  phase in structure representing a solid solution of Al 
in Mg with reduced deformability, a ductile  phase, which is a 
solid solution of Al in Li of a body centred cubic lattice, a hard - 
allowing precipitation hardening - intermetallic compound AlLi, 
and a  phase of B2 structure. The ductility of these alloys 
increases with the increasing content of  eutectic. Sometimes 
a metastable Li2MgAl phase also appears [6]. 
Basically, the strength of Mg-Li alloys in as-cast state does not 
exceed 200MPa, however, certain additives such as Zn and Y, 
forming complex phases, may increase the strength of Mg-Li 
alloys up to about 450 MPa [4]. Magnesium, like most of its 
alloys characterised by a hexagonal structure, shows lower cold 
deformability compared to aluminium alloys. In production 
practice, Mg-Al, Mg-Al-Zn and Mg-Mn alloys are mainly used. 
At high temperatures, the deformation of these alloys is also 
higher. 
Ingot homogenisation reduces the yield strength of the material, 
but the improvement of formability is insignificant, which 
generally makes these alloys of little or no applicability in plastic 
forming. Even in the extrusion process, in which there is a 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 1 ,  I s s u e  3 / 2 0 1 1 ,  1 7 - 2 0  19 
positive state of stress, cracks appear in products, thus involving 
the necessity to carry out extrusion at very low speeds.   
On the other hand, alloys from the Mg-Li group show 
superplasticity during plastic working (mostly extrusion). Some 
information about properties of these alloys can be obtained 
during the process of equal channel angular extrusion (ECAE 
process) [7, 8]. The ECAE process causes grain refinement in 
Mg-Li-Al alloys, the increase of strength and, under selected 
conditions of temperature and strain rate, the elongation in tensile 
test reaching even 300%. 
A review of the literature [3,4,5 et al.] and own investigations 
conducted by the Foundry Research Institute indicate that the 
mechanical properties of Mg-Li alloys in as-cast state are 
relatively low, which limits their practical use. However, when 
subjected to plastic forming, these alloys show a huge potential as 
regards the possibilities of obtaining higher mechanical and 
plastic properties. Therefore, studies of Mg-Li alloys subjected to 
plastic working predict the possibility of their use in the 
manufacture of components, which are required to have the 
lowest possible weight and high mechanical and plastic 
properties, to operate e.g . as parts in the ground and air transport 
means. 
Thinking of recent tendencies towards increased technical use of 
magnesium alloys, a research on the technology of melting and 
casting ultralight Mg-Li alloys has been started under Project No. 
POIG.01.03.01-00-015/09 "Advanced materials and technologies 
for their production" and under, conducted at the Foundry 
Research Institute, Task III. 5.1 Ultralight shaped sections 
extruded from the new magnesium-lithium alloys. These alloys 
will make the starting material for further plastic forming. 
 
 
2. Experimental stand for melting and 
casting of ultralight alloys in 
controlled protective atmosphere and 
for heat treatment of these alloys 
According to the research programme, the first stage of the 
experimental work was to develop the design and technological 
guidelines for the second version of the experimental stand to 
enable manufacture of the magnesium and lithium alloys. 
Considering high reactivity of these alloys, melting and casting of 
pilot samples must be carried out in a controlled atmosphere of 
protective gas, maintained in both the melting space (crucible) 
and casting chamber. This demanded the use of a crucible with 
stopper directly connected with the casting chamber, whose 
dimensions depended on the dimensions of gravity poured dies 
where samples were cast. For tests, a resistance furnace of about 5 
kW power with a 3 kg capacity crucible was provided. The 
protective atmosphere was a mixture of Ar and SF6 prepared in a 
gas mixing facility, which has been designed as an integral part of 
the whole stand. A control system used in the crucible should 
allow the temperature stabilisation with an accuracy of + / -1
0
C. It 
was also necessary to allow for the possible mechanical mixing of 
alloys in a crucible. 
Figures 2-5 show successively the design guidelines and 
making of an experimental stand for melting and casting of 
ultralight Mg-Li alloys, including an experimental furnace for a 
heat treatment of these alloys. 
 
 
 
Fig. 2. Design and operating scheme of stand for melting  
and casting of ultralight Mg-Li alloys 
 
 
 
Fig. 3. Experimental stand for melting and casting of magnesium 
and its alloys in the atmosphere of protective gas  
(a mixture of Ar+SF6) 
 
The stand for melting and casting of Mg – Li alloys has a 
modular structure including: 
a) melting module, which consists of a chamber standing on the 
casting chamber, measuring 210x210x 300 mm (width x 
length x height) made of refractory materials with two 
A R C H I V E S  o f  F O U N D R Y  E N G I N E E R I N G  V o l u m e  1 1 ,  I s s u e  3 / 2 0 1 1 ,  1 7 - 2 0  20 
heaters of 2,5 kW power and 21 Ω resistance fed by 230 V 
50 Hz current,  
b) casting chamber forms lower part of the stand and measures 
420x420x200 mm (width x length x height). The casting 
chamber is heated with a shielded heater of 1,8 kW power 
and 28 Ω resistance, mounted in the upper part of the 
chamber, 
c) gas mixing facility makes an integral part of the stand and is 
used for feeding to the crucible and casting chamber a 
mixture of protective gas composed of argon (Ar) and 
sulphur hexafluoride (SF6). 
Under this project, the design and technological guidelines were 
also developed for a small furnace designed for possible heat 
treatment of Mg-Li alloys in a protective atmosphere, including 
the following assumptions: 
 temperature in the heating chamber of up to 500°C with 
an accuracy of +/-2°C, 
 power of about 4 kV, 
 heat treatment process will be conducted in an 
atmosphere of protective gases (cooperation between 
the gas feeding facility and Mg-Li alloys melting and 
casting stand) , 
 furnace in standard equipment should have a multipoint 
temperature recorder designed for use with a PC.  
 
 
 
  
 
Fig. 4. Design of experimental furnace for the heat treatment  
of ultralight Mg-Li alloys in protective gas atmosphere 
 
 
 
Fig. 5. Experimental stand for the heat treatment of magnesium 
and its alloys in protective gas atmosphere (mixture of Ar+SF6) 
 
The experimental stands for melting, casting and heat 
treatment of ultralight alloys in controlled protective atmosphere 
enable casting ingots of the required dimensions and preset 
chemical composition from Mg-Li alloys for further plastic 
forming.  
 
 
Acknowledgements 
 
The article was prepared under Project No. POIG.01.03.01-00-
015/09 "Advanced materials and technologies for their 
production," and under, conducted at the Foundry Research 
Institute, Task III. 5.1 Ultralight shaped sections extruded from 
the new magnesium-lithium alloys. 
 
 
References 
 
[1] ASM Binary Alloy Phase Diagrams 1996 ASM 
International. 
[2] Białobrzeski A., Fajkiel A., Saja K., Dudek P., 
Experimental stand for the fabrication of ultralight alloys; 
Innowacje w Odlewnictwie Cz.I. Instytut Odlewnictwa 
Kraków, 2007 ISBN 978 88770-26-5 str. 35-39 (in Polish). 
[3] Chang T.C., Wang J.Y., Chu C.L., Lee S., Mechanical 
properties and microstructures of various Mg-Li alloys, 
Materials Letters, 60, 2006, 3272 – 3276. 
[4] Chui-Hung Chiu etc, Mikrostructural Characterization and 
Mechanical Behavior of an Mg-9%Li-1%Zn Alloys, 
Materials Science Forum Vols. 546-549 (2007) pp 229-232. 
[5] Feng Lin Ping etc; Mikrostructure, Texture and 
Deformation Behavior of Lithium Containing Magnesium 
Alloys, Materials Science Forum Vols. 475-479 (2005) pp 
481-484. 
[6] Górny Z., Sobczak J.: Advanced cast materials based on 
non-ferrous metals Wyd. ZA-PIS, Kraków, 2005.[8] Kral 
M.V. et al Crystallography of the bcc/hcp transformation in 
Mg-8Li alloy Materials Science and Engineering A vol 460-
461, 2007 str. 227 – 232 (in Polish). 
[7] Song G.S. Kral M.V.; Characterization of cast Mg-Li-Ca 
alloys – Materials Characterization 54 (2005) 279-286. 
[8] Zhong H., Feng L., Liu P., Zhou T., Design of a Mg-Li-Al-
Zn alloy by means of CALPHAD approach, J. Computer- 
Aided Materials Design, 10, 2003, 191 – 199. 
 


Experimental stand for melting and casting of ultralight Mg-Li alloys

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