Heat-resistant magnesium alloy member

Abstract

A heat-resistant magnesium alloy member having specially excellent molding property and elongation while keeping creep resistance property, which comprises 2 to 6% by weight of aluminum and 0.5 to 4% by weight of calcium, and the balance comprising magnesium and inevitable impurities, having a Ca/Al ratio of no more than 0.8, preferably no more than 0.6. The method of preparing the heat-resistant magnesium alloy member is characterized in a semi-solid injection molding at a range between a solidus temperaaature of the alloy and a liquidus temperature of the alloy.

What is claimed is:  
     
         1 . A method of molding a heat-resistant magnesium alloy member having a creep resistance property of no more than 4×10 −10 /S of minimum creep rate under the test temperature of 150° C. and the test load of 50 MPa, comprising the steps of; 
 providing aluminum and calcium;  
 preparing an alloy composition comprising 2 to 6% by weight of said aluminum and 0.5 to 4% by weight of said calcium, and no more than 2% by weight of at least one element selected from the group consisting of zinc, manganese, zirconium, and silicon, and/or no more than 4% by weight of a rare earth metal, and the balance of magnesium and inevitable impurities, wherein a Ca/Al ratio of said alloy composition is no more than 0.8 and the average particle size of the crystal is no more than 30 μm,  
 processing said alloy composition by a cutting method so that said alloy composition is in the form of metal particles or pellets into which internal strain is introduced, and  
 subjecting said alloy composition to a semi-solid injection molding by using an injection molding machine having a cylinder and a screw at a temperature range between a solidus temperature of the alloy and a liquidus temperature of the alloy, wherein a solid phase ratio in semi-solid state is no more than 30% at the time of carrying out an injection molding.  
 
     
     
         2 . The method of molding a heat-resistant magnesium alloy member according to  claim 1 , wherein said Ca/Al ratio is no more than 0.6.  
     
     
         3 . The method of molding a heat-resistant magnesium alloy member according to  claim 1 , wherein the magnesium alloy further contains 0.03 to 0.15% by weight of Sr.