4. Magnesium alloys

4.1 Benefits of magnesium

Magnesium is the lightest of the industrial metals (ρ = 1.74), i.e. 2/3 the density of aluminum. World production is around 380,000 tonnes (1998). Its low melting point (T _f = 650°C) is associated with a low modulus of elasticity (E = 45 GPa, but E /ρ = 26 like Al or steels), and a high coefficient of thermal expansion (α = 25 · 10 ^{– 6} / K close to that of aluminum).

Although its electrical conductivity is excellent, its poor resistance to corrosion means that it is not suitable for electrical applications. Its thermal conductivity is very average [ λ = 155 W/(K · m)]. Its affinity for oxygen is high (it ignites at around 300°C in finely divided...