Single-phase solid solution cast or wrought magnesium alloys

Abstract

The present invention relates to single-phase solid solution magnesium alloys suitable for the applications as cast or wrought. These alloys are prepared by multi-microalloying with rare earth elements (including gadolinium, yttrium, dysprosium, samarium, lanthanum, cerium, neodymium and praseodymium). Each alloy contains 0.5 to less than 5 wt. % rare earth elements with a content of 0.05-2.0% by weight. The total amount of rare earth elements is controlled below 5% by weight in order for economical considerations. The amount of grain refiner calcium or zirconium is in the range of 0.05-0.6% by weight. These alloys can be prepared by die casting, permanent casting, chill casting, semi-solid processes, continuous casting and continuous twin roll casting.

1 . A magnesium alloy comprising 0.5 wt. % to less than 5.0 wt. % of at least two elements selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, wherein the content of each of said elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, if present, is from 0.05 to 2.0% by weight, based on the total weight of the alloy. 
     
     
         2 . The magnesium alloy of  claim 1  further comprising an element selected from the group consisting of Zr, Ca, Zn, and mixtures thereof. 
     
     
         3 . The magnesium alloy of  claim 1  which contains no aluminium. 
     
     
         4 . The magnesium alloy of  claim 1  consisting of (a) Mg; (b) 0.5 wt. % to less than 5.0 wt. % of at least two elements selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y; and (c) optionally Zr, Ca and/or Zn; wherein the content, based on the total weight of the alloy, of each of said elements La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, if present, is from 0.05 to 2.0% by weight; and wherein the content, based on the total weight of the alloy, of each of said elements selected from the group consisting of Zr, Ca and Zr, if present, is from 0.05 to 0.6 wt. %; the remainder being magnesium. 
     
     
         5 . The magnesium alloy according to  claim 1 , wherein Gd is present in an amount by weight of 0.05 to 2.0%. 
     
     
         6 . The magnesium alloy according to  claim 1 , wherein Y is present in an amount by weight of 0.05 to 2.0%. 
     
     
         7 . The magnesium alloy according to  claim 1 , wherein Dy is present in an amount by weight of 0.05 to 2.0%. 
     
     
         8 . The magnesium alloy according to  claim 1 , wherein Sm is present in an amount by weight of 0.05 to 2.0%. 
     
     
         9 . The magnesium alloy according to  claim 1 , wherein La is present in an amount by weight of 0.05 to 0.3%. 
     
     
         10 . The magnesium alloy according to  claim 1 , wherein Ce is present in an amount by weight of 0.05 to 0.3%. 
     
     
         11 . The magnesium alloy according to  claim 1 , wherein Nd is present in an amount by weight of 0.05 to 0.3%. 
     
     
         12 . The magnesium alloy according to  claim 1 , wherein Pr is present in an amount by weight of 0.05 to 0.3%. 
     
     
         13 . The magnesium alloy according to  claim 1 , wherein Ca is present in an amount by weight of 0.05 to 0.4%. 
     
     
         14 . The magnesium alloy according to  claim 1 , wherein Zr is present in an amount by weight of 0.2 to 0.6%. 
     
     
         15 . Use of the magnesium alloys according  claim 1  as casting magnesium alloys, wrought magnesium alloys, or degradable biomaterials. 
     
     
         16 . The magnesium alloy of  claim 2 , wherein Gd is present in an amount by weight of 0.05 to 2.0%. 
     
     
         17 . A method of improving mechanical properties in a magnesium alloy comprising forming a magnesium alloy part from the composition of  claim 1  by a method selected from the group consisting of die casting, permanent casting, chill casting, a semi-solid process continuous casting, and continuous twin roll casting. 
     
     
         18 . A method improving the formability and/or room temperature ductility of a magnesium alloy part comprising forming the magnesium alloy part from the magnesium alloy composition of  claim 1 . 
     
     
         19 . A method of purifying a magnesium alloy melt comprising forming a magnesium alloy part from the magnesium alloy composition of  claim 1  to form a magnesium alloy ingot, whereby the rare earth elements from the magnesium alloy composition interact with one or more elements selected from hydrogen, oxygen, chlorine, iron, cobalt or copper, thereby forming intermetallic compounds that settle at the bottom of the ingot for removal. 
     
     
         20 . A method of improving corrosion resistance of a magnesium alloy comprising forming a magnesium alloy part from the composition of  claim 1 .