Features and challenges of Mg

Features:

  • a) The gravimetric density of Mg is about 1/4 of that of Fe and about 2/3 of that of aluminum (Al). It is the lightest element among practical metals. (See Table 1)
  • b) This element is abundant as a resource and exists especially near the surface of the earth. It is the eighth most commonly found of all the elements occupying the periodic table, and the fourth most common among practical metals.
  • c) Magnesium contains in the human body, and it has a high level of biocompatibility. So, it can potentially be used in medical materials such as stents.
  • d) Since it’s melting point is relatively low at 650℃, it is easy to melt and to recycle.
  • e) As lightweight as it is, “beams” can be made thicker, to have higher flexural rigidity compared with iron and Al.

Challenges:

Mg alloys have been deemed disadvantageous because they have lower mechanical strength at room temperature than many aerospace grade Al alloys commonly used in aircraft, such as duralumin. Even though it is light, practical application is difficult if the material is weak. Low resistance to corrosion (it tends to rust easily) and low ignition temperature have also been major issues.

表1.実用金属の比重