Heat-resistant magnesium alloy for casting and heat-resistant magnesium alloy cast product

Abstract

A heat-resistant magnesium alloy is for casting, and includes Ca in an amount of from 1 to 15% by mass, Al in a summed amount of from 4 to 25% by mass with the amount of Ca, and the balance being Mg and inevitable impurities when the entirety is taken as 100% by mass. The heat-resistant magnesium alloy is not only inexpensive, but also effects an advantage that cracks are inhibited from occurring when being cast.

What is claimed is:  
     
         1 . A heat-resistant magnesium alloy for casting, the magnesium alloy being good in terms of the castability and heat resistance, and comprising: 
 calcium (Ca) in an amount of from 1 to 15% by mass;    aluminum (Al) in a summed amount of from 4 to 25% by mass with the amount of Ca; and    the balance being magnesium (Mg) and inevitable impurities when the entirety is taken as 100% by mass.    
     
     
         2 . The heat-resistant magnesium alloy set forth in  claim 1  further comprising manganese (Mn) in an amount of from 0.1 to 1% by mass.  
     
     
         3 . The heat-resistant magnesium alloy set forth in  claim 1 , wherein a mass ratio of the Ca amount with respect to the Al amount, Ca/Al by mass, is 1 or more.  
     
     
         4 . The heat-resistant magnesium alloy set forth in  claim 1 , wherein a solidification temperature width, a temperature difference between a liquidus temperature at which a molten metal starts solidifying and a solidus temperature at which the molten metal completes solidifying, is 110° C. or less.  
     
     
         5 . The heat-resistant magnesium alloy set forth in  claim 1  being free from a rare-earth element.  
     
     
         6 . The heat-resistant magnesium alloy set forth in  claim 1  whose average crystalline grain diameter indexing the structural roughness is 18 μm or less.  
     
     
         7 . A heat-resistant magnesium alloy cast product being good in terms of the heat resistance, and produced by a process comprising the steps of: 
 pouring a molten alloy into a mold, the molten alloy comprising the heat-resistance aluminum alloy set forth in  claim 1;  and    solidifying the molten alloy by cooling it after the pouring step.    
     
     
         8 . The heat-resistant magnesium alloy cast product set forth in  claim 7  being free from a rare-earth element.  
     
     
         9 . The heat-resistant magnesium alloy cast product set forth in  claim 7  whose average crystalline grain diameter indexing the structural roughness is 18 μm or less.