Formable magnesium based wrought alloys

Abstract

Formable magnesium based wrought alloys include a magnesium based wrought alloy consisting essentially of (wt %): 0.1 to 2.0 of Zn; 0.05 to 1.5 of Ca; 0.1 to 1.0 of Zr; 0 to 1.3 of a rare earth element or mixture of the same of which includes Gd or Y; 0 to 0.3 of Sr, Al: 0 to 0.7; the balance of Mg and other unavoidable impurities.

What is claimed is: 
     
         1 . A magnesium based wrought alloy consisting essentially of (wt %):
 0.1 to 2.0 of Zn;   0.05 to 1.5 of Ca;   0.1 to 1.0 of Zr;   0 to 1.3 of a rare earth element or mixture of the same of which includes Gd or Y;   0 to 0.3 of Sr;   0 to 0.7 of Al,   the balance of Mg and other unavoidable impurities.   
     
     
         2 . The alloy according to  claim 1 , wherein the rare earth element mixture comprises gadolinium or yttrium and a rare earth element of the lanthanide series. 
     
     
         3 . The alloy according to  claim 1 , wherein the rare earth element mixture comprises gadolinium and La. 
     
     
         4 . The alloy according to  claim 1 , wherein the rare earth element consists essentially of gadolinium. 
     
     
         5 . A magnesium based wrought alloy consisting essentially of (wt %):
 Zn: 0.1 to 2.0;   Ca: 0.05 to 1.5;   Zr: 0.1 to 1.0;   Gd: 0 to 1.0;   Sr: 0 to 0.3;   La: 0 to 0.3;   Al: 0 to 0.7; and   the balance of Mg and other unavoidable impurities.   
     
     
         6 . The magnesium based wrought alloy according to  claim 1 , consisting essentially of (wt %):
 Zn: 0.3 to 1.0;   Ca: 0.3 to 1.0;   Zr: 0.2 to 0.7;   Gd: 0.1 to 0.5;   Sr: 0 to 0.2;   La: 0 to 0.2;   Al: 0 to 0.5; and   the balance of Mg and other unavoidable impurities.   
     
     
         7 . The magnesium based wrought alloy according to  claim 1 , comprising a Mg—Zn—Gd—Ca—Zr based alloy consisting essentially of (wt %):
 Zn: 0.5 to 2.0; 
 Ca: 0.05 to 1.0; 
 Zr: 0.1 to 1.0; 
 Gd: 0.05 to 1.0; 
 Sr: 0 to 0.3; 
 La: 0 to 0.3; 
 Al: 0 to 0.7 and 
 the balance of Mg and other unavoidable impurities. 
 
     
     
         8 . The magnesium based wrought alloy according to  claim 7 , comprising a Mg—Zn—Gd—Ca—Zr based alloy consisting essentially of (wt %):
 Zn: 0.5 to 1.5; 
 Ca: 0.1 to 0.7; 
 Zr: 0.2 to 0.7; 
 Gd: 0.1 to 0.5; 
 Sr: 0 to 0.2; 
 La: 0 to 0.2; 
 Al: 0.2 to 0.5 and 
 the balance of Mg and other unavoidable impurities. 
 
     
     
         9 . The magnesium based wrought alloy according to  claim 1 , comprising a Mg—Ca—Zn—(Zr) based alloy consisting essentially of (wt %):
 Ca: 0.3 to 1.5; 
 Zn: 0.1 to 0.8; 
 Zr: 0.1 to 1.0; 
 Gd: 0 to 1.0; 
 Al: 0 to 0.7; 
 Sr: 0 to 0.3; and 
 the balance of Mg and other unavoidable impurities. 
 
     
     
         10 . The magnesium based wrought alloy according to  claim 9 , comprising a Mg—Ca—Zn—(Zr) based alloy consisting essentially of (wt %):
 Ca: 0.6 to 1.0; 
 Zn: 0.3 to 0.5; 
 Zr: 0.2 to 0.7; 
 Gd: 0 to 0.5; 
 Al: 0.2 to 0.5; 
 Sr: 0 to 0.2; and 
 the balance of Mg and other unavoidable impurities. 
 
     
     
         11 . The magnesium based wrought alloy according to  claim 1 , wherein the total weight % of alloying elements is less than 4%. 
     
     
         12 . The magnesium based wrought alloy according to  claim 1 , further comprising: 0.05 to 0.7 Mn. 
     
     
         13 . The magnesium based wrought alloy according to  claim 1 , wherein the magnesium based alloy comprises incidental impurities having less than 0.5% by weight. 
     
     
         14 . The magnesium based wrought alloy according to  claim 1 , wherein the magnesium based alloy comprises incidental impurities having less than 0.2% by weight. 
     
     
         15 . The magnesium based wrought alloy according to  claim 1 , selected from the group consisting of Mg-1Zn-0.4Gd-0.2Ca-0.5Zr and Mg-0.8Ca-0.4Zn-0.1 Sr-0.4Gd-0.5Zr. 
     
     
         16 . A magnesium based wrought alloy sheet comprising at least one magnesium based wrought alloy according to  claim 1 . 
     
     
         17 . A method of fabricating a magnesium based alloy sheet product, the method comprising:
 providing a magnesium alloy melt from the magnesium-based alloy according to  claim 1 ;   casting said magnesium alloy melt into a slab or a strip according to a predetermined thickness;   homogenising or preheating said cast slab or strip;   successively hot rolling said homogenised or preheated slab or strip at a suitable temperature to reduce said thickness of said homogenised slab or strip to produce an alloy sheet product of a predetermined thickness; and   annealing said alloy sheet product at a suitable temperature for a period of time.   
     
     
         18 . The method of  claim 17 , wherein the casting comprises feeding the magnesium alloy melt between rolls of a twin-roll caster to create a strip. 
     
     
         19 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the homogenising or preheating of the cast slab or strip occurs at a temperature between 300 to 500° C. 
     
     
         20 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the homogenising or preheating of the cast slab or strip is followed by quenching. 
     
     
         21 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein hot rolling is conducted in the temperature range of 300 to 550° C. 
     
     
         22 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the hot rolling results in a total thickness reduction of 50 to 95%. 
     
     
         23 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the hot rolling is conducted using a plurality of rolling passes, in which after each rolling pass, the sheets are reheated at a temperature in the range of 350 to 500° C. prior to subsequent rolling. 
     
     
         24 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the casting comprises pouring the magnesium alloy melt into one of a direct chill (DC) caster, a sand caster, or a permanent mould caster. 
     
     
         25 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , further comprising subjecting the annealed alloy to an age hardening treatment comprising heating the alloy at 150° C. for at least 1 hour. 
     
     
         26 . The magnesium based wrought alloy according to  claim 1 , wherein the total weight % of alloying elements is less than 3%. 
     
     
         27 . The magnesium based wrought alloy according to  claim 1 , further comprising 0.1 to 0.5 Mn. 
     
     
         28 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the homogenising or preheating of the cast slab or strip is followed by water quenching. 
     
     
         29 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein hot rolling is conducted in the temperature range of 350 to 500° C. 
     
     
         30 . The method of fabricating a magnesium based alloy sheet product according to  claim 17 , wherein the hot rolling results in a total thickness reduction of 70 to 80%.