Method for producing grain refined magnesium and magnesium-alloys

Abstract

The present invention relates to a method for producing grain refined Mg and Mg alloys by solidifying molten Mg or Mg-alloys in the presence of ZrB 2 or ZrC particles leading to a grain refined microstructure. The particles have an average particles size less than 20 μm and larger 0.1 μm and are either produced by an in situ formation within the melt or by a high temperature treatment of an intimate mixtures of zirconium oxide and carbon black and in case of ZrB 2 additionally a suitable boron source like boron carbide or boron oxide or boron followed by a milling and de-agglomeration procedure. The method according to the invention leads to grain refined Mg or Mg alloys with an average grain size less than 100 μm.

1 . A method for producing grain refined Mg and Mg alloys by solidifying molten Mg or molten Mg alloys in presence of a nucleation agent, wherein a nucleation agent ZrB 2  and/or ZrC is used. 
     
     
         2 . A method according to  claim 1 , wherein said nucleation agent has a particle size within the range of about 0.1 μm and about 20 μm. 
     
     
         3 . A method according to  claim 2 , wherein said nucleation agent is added to the molten Mg or Mg alloy. 
     
     
         4 . A method according to  claim 2 , wherein said nucleation agent is produced within the molten Mg or Mg alloy. 
     
     
         5 . A method according to  claim 2 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         6 . A method according to  claim 2 , wherein said nucleation agent has a particle size within the range of about 1 μm and about 4 μm. 
     
     
         7 . A method according to  claim 6 , wherein said nucleation agent is added to the molten Mg or Mg alloy. 
     
     
         8 . A method according to  claim 6 , wherein said nucleation agent is produced within the molten Mg or Mg alloy. 
     
     
         8 . A method according to  claim 6 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         9 . A method according to  claim 1 , wherein said nucleation agent is added to the molten Mg or Mg alloy. 
     
     
         10 . A method according to  claim 9 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         11 . A method according to  claim 1 , wherein said nucleation agent is produced within the molten Mg or Mg alloy. 
     
     
         12 . A method according to  claim 11 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         13 . A method according to  claim 1 , wherein said nucleation agent is added to the molten Mg or Mg alloy. 
     
     
         14 . A method according to  claim 13 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         15 . A method according to  claim 1 , wherein at least one of ZrB 2  and ZrC is present in the molten Mg or Mg alloy in a concentration within the range of about 0.01 wt. % and about 1 wt. 
     
     
         16 . A method according to  claim 1 , wherein said molten Mg alloy and a Mg—Al alloy is used.