Method for providing magnesium alloys with superplastic properties

Abstract

The invention relates to a method for producing magnesium alloys with a superplastic structure using a deformation process, followed by quick cooling. The magnesium-based alloy is initially pre-heated to a temperature of 340-380° C. and is subsequently deformed. The semi-finished product thus obtained is cooled down at high speed to an ambient temperature immediately after deformation.

1 . A method for producing magnesium alloys with a superplastic microstructure, which comprises the following steps: 
 a) Heating a magnesium-based alloy to a temperature of 250 to 600° C.,    b) working the cooled alloy to form a semifinished product at a temperature of 250 to 450° C.,    c) immediately and rapidly cooling the semifinished product using cooling rates of greater than 300° C./min.    
     
     
         2 . The method as claimed in  claim 1 , characterized in that in step a) the alloy is heated to a temperature of 340 to 380° C.  
     
     
         3 . The method as claimed in  claim 1  or  2 , characterized in that the extrudate is quenched immediately at a cooling rate of 6000° C./min.  
     
     
         4 . A method for producing magnesium alloys having a superplastic microstructure, which comprises the following steps: 
 f) Heating a magnesium-based alloy to a temperature of 300 to 550° C. and holding this temperature for 1 to 100 hours,    g) cooling the heated alloy to a temperature of 0 to 100° C.,    h) reheating the cooled alloy to a temperature of 200 to 400° C. and holding this temperature for 1 to 100 hours,    i) cooling the reheated alloy in air to a temperature of 0 to 100° C.,    j) working the cooled alloy to form a semifinished product at a temperature of 250 to 450° C.    
     
     
         5 . The method as claimed in  claim 4 , characterized in that in step a) the alloy is heated to a temperature of 390 to 420° C.  
     
     
         6 . The method as claimed in  claim 4  or  5 , characterized in that in step c) the alloy is heated to a temperature of 250 to 310° C.  
     
     
         7 . The method as claimed in  claim 4 ,  5  or  6 , characterized in that in step b) and/or d) the alloy is cooled to ambient temperature.  
     
     
         8 . The method as claimed in one of  claims 4  to  7 , characterized in that in step a) and/or b) the heated alloy is held at the final temperature for 12 to 24 hours.  
     
     
         9 . The method as claimed in one of the preceding claims, characterized in that the magnesium-based alloy in addition to magnesium also contains aluminum, zinc, manganese, silicon, copper, zirconium, silver and/or rare earths.  
     
     
         10 . The method as claimed in one of the preceding claims, characterized in that the alloy is worked by extrusion.  
     
     
         11 . The method as claimed in  claim 10 , characterized in that the pressing ratio during the extrusion is 1:25 to 1:50.  
     
     
         12 . The method as claimed in  claim 10  or  11 , characterized in that the billet temperature and the receptacle temperature during the extrusion is 300 to 400° C.