Magnalium
Encyclopedia
Magnalium is an aluminium
alloy
with 1.5 to 2% magnesium
and small amounts of copper
, nickel
, and tin
. Some alloys, intended for particular uses at the cost of poor corrosion resistance, may consist of up to 50% magnesium. It finds use in engineering and pyrotechnics
.
resistance, and lower density
than pure aluminium. Such alloys are also more workable and easier to weld than pure aluminium. Alloys with high amounts of magnesium (around 50%) are brittle and more susceptible to corrosion than aluminium.
and automobile
parts. Alloys with about 50% magnesium are brittle and corrode easily, which makes them unsuitable for most engineering uses. However, these alloys are flammable when powdered, are more resistant to corrosion than pure magnesium, and are more reactive than pure aluminium and are therefore used in pyrotechnics
as a metal fuel
and to produce sparks. Magnalium powder also burns with a crackling sound if burnt by itself, and provides a good compromise between the reactivity of Magnesium, and the stability of Aluminum. Another benefit for pyrotechnics is the brittleness of the alloy, as mentioned before. It is easily broken with a hammer and then ground in a coffee grinder to usable powder. It will grind in a ball mill into a fine powder in a matter of hours, as opposed to a matter of days with aluminium powder.
Although it must be noted that it is much more powerful than Aluminium powder (when compared at similar mesh size) and similar precautions should be taken as per magnesium. These include dangers of moisture and incompatibility with other compounds (boric acid and ammonium compounds).
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
with 1.5 to 2% magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
and small amounts of copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
, and tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
. Some alloys, intended for particular uses at the cost of poor corrosion resistance, may consist of up to 50% magnesium. It finds use in engineering and pyrotechnics
Pyrotechnics
Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...
.
Properties
Alloys with smaller amounts of magnesium (about 5%) exhibit greater strength, greater corrosionCorrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
resistance, and lower density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
than pure aluminium. Such alloys are also more workable and easier to weld than pure aluminium. Alloys with high amounts of magnesium (around 50%) are brittle and more susceptible to corrosion than aluminium.
Uses
Although they are generally more expensive than aluminium, the high strength, low density, and greater workability of alloys with low amounts of magnesium leads to their use in aircraftAircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
and automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
parts. Alloys with about 50% magnesium are brittle and corrode easily, which makes them unsuitable for most engineering uses. However, these alloys are flammable when powdered, are more resistant to corrosion than pure magnesium, and are more reactive than pure aluminium and are therefore used in pyrotechnics
Pyrotechnics
Pyrotechnics is the science of using materials capable of undergoing self-contained and self-sustained exothermic chemical reactions for the production of heat, light, gas, smoke and/or sound...
as a metal fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
and to produce sparks. Magnalium powder also burns with a crackling sound if burnt by itself, and provides a good compromise between the reactivity of Magnesium, and the stability of Aluminum. Another benefit for pyrotechnics is the brittleness of the alloy, as mentioned before. It is easily broken with a hammer and then ground in a coffee grinder to usable powder. It will grind in a ball mill into a fine powder in a matter of hours, as opposed to a matter of days with aluminium powder.
Although it must be noted that it is much more powerful than Aluminium powder (when compared at similar mesh size) and similar precautions should be taken as per magnesium. These include dangers of moisture and incompatibility with other compounds (boric acid and ammonium compounds).
External links
- http://pyroguide.com/index.php?title=Magnalium
- Making Magnalium
- http://www.thegreenman.me.uk/pro/magnalium.html