Magnesium alloy and method for manufacturing the same

Abstract

Disclosed are a highly versatile magnesium alloy that can achieve both formability and strength in a temperature range including room temperature, and a method for manufacturing the magnesium alloy, wherein the obtained magnesium alloy contains 0.2 to 2 wt % of Al, 0.2 to 1 wt % of Mn, 0.2 to 2 wt % of Zn, and at least 0.2 to 1 wt % of Ca, the remainder comprising Mg and unavoidable impurities, and a precipitate comprising Mg, Ca, and Al is dispersed on the (0001) plane of a magnesium matrix.

What is claimed is: 
     
         1 . A magnesium alloy, comprising:
 0.2 to 2 wt % or less of Al,   0.2 to 1 wt % or less of Mn,   0.2 to 2 wt % of Zn, and   at least 0.2 to 1 wt % of Ca,   the remainder comprising Mg and unavoidable impurities,   wherein   a precipitate comprising Mg, Ca, and Al is dispersed on the (0001) plane of a magnesium matrix.   
     
     
         2 . The magnesium alloy as set forth in  claim 1 , further containing a precipitate comprising Al and Mn. 
     
     
         3 . The magnesium alloy as set forth in  claim 1 , wherein the precipitate comprising Mg, Ca, and Al has a plate-like shape, a longer side of the plate falls within a range from 3 to 6 nm, and the number density of the precipitate falls within a range from 10 20  to 10 24 /m 3 . 
     
     
         4 . The magnesium alloy as set forth in  claim 1 , wherein the average grain size of the magnesium matrix is 20 μm or less. 
     
     
         5 . The magnesium alloy as set forth in  claim 1 , wherein the basal texture intensity of the (0002) pole on a normalized RD-TD face of the (0002) pole figure measured by the X-ray diffraction is 5.0 mrd or less. 
     
     
         6 . The magnesium alloy as set forth in  claim 1 , wherein the Index Erichsen value at room temperature is 6.5 mm or higher. 
     
     
         7 . The magnesium alloy as set forth in  claim 1 , wherein the 0.2% proof strength of a material having undergone solution treatment is 120 MPa or higher. 
     
     
         8 . The magnesium alloy as set forth in  claim 1 , wherein the 0.2% proof strength of a material having undergone aging treatment is 160 MPa or higher. 
     
     
         9 . The magnesium alloy as set forth in  claim 1 , wherein the elongation to failure is 20% or higher. 
     
     
         10 . A method for manufacturing a magnesium alloy, comprising:
 process 1 for melting Mg, Al, Mn, Zn, and Ca to obtain a cast ingot;   process 2 for subjecting the cast ingot to a homogenization treatment to obtain a homogenized ingot;   process 3 for subjecting the homogenized ingot to hot or warm working to obtain a material;   process 4 for subjecting the material to a solution treatment to obtain a solution treated sample; and   process 5 for subjecting the solution treated sample to an aging treatment to obtain a magnesium alloy, wherein   the homogenization treatment is performed at a temperature ranging from 400° C. to 500° C. for a specified time period in the process 2 to obtain the homogenized ingot, and   the aging treatment is performed at a temperature ranging from 140 to 250° C. for a specified time period in the process 5 to obtain the magnesium alloy.   
     
     
         11 . The method for manufacturing a magnesium alloy as set forth in  claim 10 , wherein a secondary working process for subjecting the solution treated sample to secondary processing is included between the process 4 and the process 5. 
     
     
         12 . The method of manufacturing a magnesium alloy as set forth in  claim 10 , wherein the solution treated sample having the 0.2% proof strength of 120 MPa or higher is subjected to a secondary processing, and the 0.2% proof strength is increased to 160 MPa or higher by the process 5. 
     
     
         13 . The method for manufacturing a magnesium alloy as set forth in  claim 10 , wherein the aging treatment is performed in the process 5 to increase the hardness of the magnesium alloy.