Mag-Thor is the common name for a range of

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

(Mg)

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

s containing

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

(Th) that are used in

aerospace engineering Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is si ...

Alloys

These alloys commonly contain

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

and

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

, but there are other combinations known. Some common alloys are named HK31, HM21, HM31, HZ32, ZH42, ZH62; where the "H" indicates that the alloy contains thorium. Magnesium alloy names are often given by two letters following by two numbers. The two letters indicate the main elements present in the alloy where A = aluminum, Z = zinc, M = manganese, S = silicon, etc. the numbers tell percentage compositions of the two elements. So, AZ31 would indicate that there is 3% aluminum and 1% zinc in the alloy. Magnesium-thorium alloys have been used in several military applications, particularly in missile construction. The most noted example of this is the ramjet components in the CIM-10

Bomarc The Boeing CIM-10 BOMARC (Boeing Michigan Aeronautical Research Center) (IM-99 Weapon System prior to September 1962) was a supersonic ramjet powered long-range surface-to-air missile (SAM) used during the Cold War for the air defense of North ...

missile and

Lockheed D-21 The Lockheed D-21 is an American supersonic reconnaissance drone. The D-21 was initially designed to be launched from the back of an M-21 carrier aircraft, a variant of the Lockheed A-12 aircraft. The drone had maximum speed in excess of at a ...

drone, which implemented thoriated magnesium in their engine construction. This is due to thoriated magnesium alloys being lightweight, having high strength, and creep resistance up to 350 °C. But, these alloys are no longer used due to radiation concerns involving thorium's radioactivity. This has resulted in several missiles being removed from public display. Similarly, the structure of the Equipment and Retro-Rocket Modules of the Gemini spacecraft (the white-painted portions) were made of thoriated magnesium for their strength-to-weight ratio and thermal properties. These were not part of the inhabited cabin, though the radiator tubing, whose silicone coolant flowed through the cabin, was also made of the same material. All examples burned up in the atmosphere upon reentry. Another concern for the thoriated magnesium alloys is the low melting point and rapid oxidation of the metal. This can result in dangerous flash fires during the production of the alloys. Additionally, thorium-free magnesium alloys have been developed that exhibit similar characteristics to mag-thor, causing currently used magnesium-thorium alloys to be cycled out of use.

External links

Oak Ridge Associated Universities article on Mag-Thor alloys
* ttp://www.magnesium.com/w3/data-bank/index.php?mgw=165 basic commercial magnesium alloys Magnesium alloys

Alloys

Further reading

External links