Magnesium Alloys Overview
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Magnesium is most commonly alloyed with other metals when being used in structural applications. The following table displays a number of commonly used alloying elements alongside their effects upon the resulting metal. Many alloying elements can be useful in a variety of different applications whereas others are only ideal for very specific applications due to the change in properties.

Alloying Element

Effects of Addition

  • most widely used in alloying due to numerous favorable effects
  • increases hardness, strength and castability while only increasing density minimally
  • average alloy contains about 2-9 weight percent of aluminum and can be heat treated with > 6 weight percent
  • increased amount of aluminum decreases the ductility of the alloy
  • included only in very small quantities
  • significantly reduces surface melt oxidation during processing
  • grain coarsening can occur
  • can be a carcinogenic material and is being rejected by some companies for use
  • improves thermal and mechanical properties as well as assists in grain refinement and creep resistance
  • reduces oxidation during processing when added to cast alloys
  • allows for better rollability of sheet metal
  • additions exceeding .3 weight percent, increases the risk of cracking during welding
  • reduces surface tension
  • improves corrosion resistance
  • increases plastic deformation capability, magnesium elongation, and work hardening rates
  • reduces yield strength
  • assists in increasing both room and high temperature strength
  • negatively impacts ductility and corrosion resistance
  • increases saltwater corrosion resistance within some aluminum containing alloys
  • reduces the adverse effects of iron, usually present in .2-.4 weight percent
  • increases both yield and ultimate strength at room temperature
  • negatively impacts ductility and corrosion resistance
  • improves material strength
Rare Earth Metals
  • increase in high temperature creep and corrosion resistance and strength
  • allows lower casting porosity and weld cracking in processing
  • can increase molten alloys’ fluidity
  • improves elevated temperature properties, especially creep resistance
  • only used in pressure die casting
  • used in conjunction with other elements to enhance creep performance
  • when used with aluminum it improves ductility, and reduces tendency to crack during processing
  • enhances high temperature strength and creep performance when combined with other rare earth metals
  • second most commonly used alloying metal with magnesium
  • increases the alloys’ fluidity in casting
  • when added to magnesium alloys with nickel and iron impurities, it can improve corrosion resistance
  • additions of 2 weight percent or greater tend to be prone to hot cracking
  • refines grain size in sand and gravity castings (not combined with aluminum)

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