Magnesium alloys having long-period stacking order phases
Magnesium alloys comprising a long period stacking order (LPSO) phase having an 14H-i or an 18R-i structure are provided. The alloys comprise magnesium as a majority element, a first alloying element that is larger than magnesium and a second alloying element that is smaller than magnesium.
1. A magnesium alloy comprising a long period stacking order structural phase having a 14H-i structure with a Mg 71 X L 8 X S 6 composition that includes Mg at an interstitial site or having a 18R-i structure with a Mg 59 X L 8 X S 6 composition that includes Mg at an interstitial site, wherein the stable 14H-i and the 18R-i structures have negative formation energies and are more stable than any combination of every other phase in their ternary system,
wherein X L comprises a rare earth alloying element selected from Sc, Y, Pm, Sm, Tb, Dy, Ho, Er, Tm, and Lu and X S comprises a second alloying element selected from Al, Zn, Cu, Ni, and Co, and
further wherein if X s is Al, X L is Y, Pm, Sm, Tb, Dy, Ho, Er, Tm or Lu; if is X s is Zn, X L is Sc, Pm, Sm or Lu; if X s is Cu, X L is Sc or Lu; if X s is Ni, X L is Sc, Pm, Sm or Lu; and if X s is Co, X L is Pm or Lu.
2. The magnesium alloy of claim 1 , wherein X s is Al and X L is Y, Pm, Sm, Tb, Dy, Ho, Er, Tm or Lu.
3. The magnesium alloy of claim 1 , wherein X s is Zn, Cu, or Ni and X L is Sc.
4. The magnesium alloy of claim 1 , wherein X s is Al, Zn, Ni, or Co and X L is Pm.
5. The magnesium alloy of claim 1 , wherein X s is Al, Zn, or Ni and X L is Sm.
6. The magnesium alloy of claim 1 , wherein X s is Al, Zn, Cu, Ni, or Co and X L is Lu.