Magnesium is the most lightweight structural metal that can be employed in industry. Its casting alloys are increasingly used for those functions when light weight is an issue. It can also be an economic alternative to zamak or aluminium, depending on the characteristics of the parts. Compared to polymers, magnesium has all the advantages of metals and its density is only slightly higher.

Main advantages with respect to other alloys:

  • Its density is 33% lower than aluminium alloys; and 73% lower than zamak: Very lightweight parts; for those uses in which this property is required, and also lower transport costs and it is easier to handle.
  • Longer duration of the die than one for aluminium (three or four times longer), lower replacement and maintenance costs off the dies.
  • The highest machining speed of all metals: higher production when secondary operations are required.
  • Higher vibration absorption. Ideal for those uses in which this property is required. Less noise when handling parts.
  • Compatibility and costless interchangeability with zamak dies, since both use the same hot chamber technology.
  • … and a marketing appeal, for its “novelty” status, ideal for sports equipment applications etc.

Main characteristics of commercial alloy MAGNESIUM AZ91D

Magnesium Chemical Composition

In accordance with standard: DIN 1729 3.5912

Chemical Composition (%)
Aluminium Al 8,3   -   9,7
Manganese Mn Min.   0,15
Zinc Zn 0,35   -   1
Silicon Si max.   0,10
Iron Fe max.   0,005
Copper Cu max.   0,030
Nickel Ni max.   0,002
Others - max.   0,02
Physical Properties
Density at 20ºC g/cm³ 1,81
Fusion Interval ºC 470 - 595
Casting Temperature ºC 625 - 700
Contraction at solidification mm/m Less than zamak
Expansion coefficient x 10-6 K-1 26
Fusion heat KJ/kg -
Specific heat J/kg x K 1050
Thermal conductivity W/m x K< 72
Electrical conductivity % IACS 12.2
Mechanical Properties for hot chamber cast parts
Tensile Strength N/mm² 24
Elongation % 3
Brinell hardness   63  - 70
Impact resistance J 6

*These properties given are for information purposes only and differ depending on the sape of the part and casting parameters.

Comparison of alloy properties

Density 6.7 2.7 1.8