Magnesium alloy, magnesium alloy member and method for manufacturing same, and method for using magnesium alloy

Abstract

A magnesium alloy of the present invention has the chemical composition that contains 0.02 mol % or more and less than 0.1 mol % of at least one element selected from yttrium, scandium, and lanthanoid rare earth elements, and magnesium and unavoidable impurities accounting for the remainder. A magnesium alloy member of the present invention is produced by hot plastic working of the magnesium alloy in a temperature range of 200° C. to 550° C., followed by an isothermal heat treatment performed in a temperature range of 300° C. to 600° C. The magnesium alloy is preferred for use in applications such as in automobiles, railcars, and aerospace flying objects. The magnesium alloy and the magnesium alloy member can overcome the yielding stress anisotropy problem, and are less vulnerable to the rising price of rare earth elements.

1 . A magnesium alloy comprising 0.02 mol % or more and less than 0.1 mol % of at least one element selected from yttrium, scandium, and lanthanoid rare earth elements, and Mg and unavoidable impurities accounting for the remainder. 
     
     
         2 . A magnesium alloy member comprising the magnesium alloy of the chemical composition of  claim 1 , wherein the crystal structure of the member is an equiaxial grain structure with no texture. 
     
     
         3 . (canceled) 
     
     
         4 . The magnesium alloy member according to  claim 2 , wherein the average grain size is 10 μm or more. 
     
     
         5 . The magnesium alloy member according to  claim 2 , wherein a compressional nominal strain of 0.4 or more is applied by cold working performed in a temperature range of from room temperature to 150° C. 
     
     
         6 . The magnesium alloy member according to  claim 2 , wherein the average grain size of the magnesium alloy after cold working performed in a temperature range of from room temperature to 150° C. is 80% or less of the average grain size of an unworked magnesium alloy. 
     
     
         7 . The magnesium alloy member according to  claim 2 , wherein the strength and hardness of the member after applying nominal strain by cold working performed in a temperature range of from room temperature to 150° C. are 15% greater than strength and hardness of the undeformed ones. 
     
     
         8 . A method for producing a magnesium alloy member, the method comprising:
 hot plastic working of a magnesium alloy that contains 0.02 mol % or more and less than 0.1 mol % of at least one element selected from yttrium, scandium, and lanthanoid rare earth elements, and Mg and unavoidable impurities accounting for the remainder, the hot plastic working being performed in a temperature range of 200° C. to 550° C.; and   an isothermal heat treatment of the magnesium alloy in a temperature range of 300° C. to 600° C. after the hot plastic working.   
     
     
         9 . A method for using a magnesium alloy that contains 0.02 mol % or more and less than 0.1 mol % of at least one element selected from yttrium, scandium, and lanthanoid rare earth elements, and Mg and unavoidable impurities accounting for the remainder,
 the method using the magnesium alloy as a wrought magnesium member after hot plastic working performed in a temperature range of 200° C. to 550° C., and a subsequent isothermal heat treatment performed in a temperature range of 300° C. to 600° C.