Magnesium alloy and production process thereof

Abstract

Provided are a magnesium alloy which is inexpensive, can be produced at a high yield, and has both high strength and high ductility; and a production process of the magnesium alloy. The magnesium alloy contains from 1 to 4 atomic % of Zn and from 1 to 4.5 atomic % of Y at a Zn/Y composition ratio ranging from 0.6 to 1.3, and contains both an intermetallic compound Mg 3 Y 2 Zn 3 , and Mg 12 YZn having a long period structure. It may contain from 2 to 3.5 atomic % of Zn and from 2 to 4.5 atomic % of Y at a Zn/Y composition ratio falling within a range of from 0.8 to 1.2. It may contain from 1 to 4 atomic % of Zn, from 1 to 4.5 atomic % of Y and from 0.1 to 0.5 atomic % of Zr and contains, as a remaining portion, Mg and inevitable impurities. An alloy structure having both an intermetallic compound Mg 3 Y 2 Zn 3 and Mg 12 YZn having a long period structure is available by casting an Mg alloy containing from 1 to 4 atomic % of Zn and from 1 to 4.5 atomic % of Y at a Zn/Y composition ratio ranging from 0.6 to 1.3, followed by plastic processing.

What is claimed is:  
     
         1 . A magnesium alloy, which comprises, based on a total alloy amount, from 1 to 4 atomic % of Zn and from 1 to 4.5 atomic % of Y at a Zn/Y composition ratio falling within a range of from 0.6 to 1.3, and includesv an intermetallic compound Mg 3 Y 2 Zn 3  and Mg 12 YZn having a long period structure.  
     
     
         2 . A magnesium alloy according to  claim 1 , which comprises at least 3 atomic % of Zn and at least 3 atomic % of Y, each based on a total alloy amount, and as a remaining portion Mg and inevitable impurities.  
     
     
         3 . A magnesium alloy according to  claim 1 , which comprises from 2 to 3.5 atomic % of Zn and from 2 to 4.5 atomic % of Y, each based on a total alloy amount, at a Zn/Y composition ratio falling within a range of from 0.8 to 1.2.  
     
     
         4 . A magnesium alloy according to  claim 3 , which comprises at least 3 atomic % of Zn and at least 3 atomic % of Y, each based on a total alloy amount, and as a remaining portion Mg and inevitable impurities.  
     
     
         5 . A magnesium alloy according to  claim 1 , which comprises from 1 to 4 atomic % of Zn, from 1 to 4.5 atomic % of Y, and from 0.1 to 0.5 atomic % of Zr, each based on a total alloy amount, and as a remaining portion Mg and inevitable impurities.  
     
     
         6 . A production process of a magnesium alloy, which comprises casting an Mg alloy comprising from 1 to 4 atomic % of Zn and from 1 to 4.5 atomic % of Y at a Zn/Y composition ratio falling within a range of from 0.6 to 1.3; and plastic processing of the cast product obtained in the above-described step into an alloy structure containing an intermetallic compound Mg 3 Y 2 Zn 3  and Mg 12 YZn having a long period structure.  
     
     
         7 . A production process of a magnesium alloy according to  claim 6 , which comprises at least 3 atomic % of Zn and at least 3 atomic % of Y, each based on a total alloy amount, and as a remaining portion Mg and inevitable impurities.  
     
     
         8 . A production process of a magnesium alloy according to  claim 6 , which comprises from 2 to 3.5 atomic % of Zn and from 2 to 4.5 atomic % of Y, each based on a total alloy amount, at a Zn/Y composition ratio falling within a range of from 0.8 to 1.2.  
     
     
         9 . A production process of a magnesium alloy according to  claim 8 , wherein the magnesium alloy contains at least 3 atomic % of Zn and at least 3 atomic % of Y, each based on a total alloy amount and contains as a remaining portion Mg and inevitable impurities.  
     
     
         10 . A production process of a magnesium alloy according to  claim 6 , wherein the magnesium alloy contains from 1 to 4 atomic % of Zn, from 1 to 4.5 atomic % of Y and from 0.1 to 0.5 atomic % of Zr, each based on a total alloy amount and contains as a remaining portion Mg and inevitable impurities.  
     
     
         11 . A production process of a magnesium alloy according to  claim 6 , wherein the casting is performed at a cooling rate of 10 K/sec or less.  
     
     
         12 . A production process of a magnesium alloy according to  claim 6 , wherein the plastic processing is carried out by extrusion of the cast product.