Raw Magnesium Alloy Powder Material, Magnesium Alloy with High Proof Stress, Manufacturing Method of Raw Magnesium Alloy Powder Material and Manufacturing Method of Magnesium Alloy with High Proof Stress

Abstract

A raw magnesium alloy powder material having a relatively small crystal grain diameter is obtained by subjecting a starting material powder having a relatively large crystal grain diameter to a plastic working in which the powder is passed through a pair of rolls to undergo compressive deformation or shear deformation. The starting material powder is a magnesium alloy powder having a fine intermetallic compound ( 21 ) precipitated and dispersed in a base ( 22 ) by a heat treatment. A work strain ( 22 ) is formed around the precipitated intermetallic compound ( 21 ) in the magnesium alloy powder after processed by the plastic working. The magnesium alloy powder after processed by the plastic working has a maximum size of 10 mm or less and a minimum size of 0.1 mm or more, and the magnesium particle constituting the base ( 20 ) has a maximum crystal grain diameter of 20 μm or less.

1 . A raw magnesium alloy powder material having a relatively small crystal grain diameter obtained by subjecting a starting material powder having a relatively large crystal grain diameter to a plastic working in which the powder is passed through a pair of rolls to undergo compressive deformation or shear deformation, characterized in that
 said starting material powder is a magnesium alloy powder having a fine intermetallic compound precipitated and dispersed in a base by a heat treatment,   a work strain is formed around said precipitated intermetallic compound in said magnesium alloy powder after processed by said plastic working,   the magnesium alloy powder after processed by said plastic working has a maximum size of 10 mm or less and a minimum size of 0.1 mm or more, and   a magnesium particle constituting the base of said magnesium alloy powder after processed by the plastic working has a maximum crystal grain diameter of 20 μm or less.   
     
     
         2 . The raw magnesium alloy powder material according to  claim 1 , wherein
 said intermetallic compound is at least one compound selected from a group consisting of Mg 17 Al 12 , Al 2 Ca, Mg 2 Si, MgZn 2 , Al 3 Re (Re: rare-earth element), Al 11 Re 3 , and Al 6 Mn.   
     
     
         3 . The raw magnesium alloy powder material according to  claim 1 , wherein
 said intermetallic compound has a maximum grain diameter of 5 μm or less.   
     
     
         4 . The raw magnesium alloy powder material according to  claim 1 , wherein
 said intermetallic compound has a maximum grain diameter of 2 μm or less.   
     
     
         5 . The raw magnesium alloy powder material according to  claim 1 , wherein
 said magnesium particle constituting the base of said magnesium alloy powder has a maximum crystal grain diameter of 10 μm or less.   
     
     
         6 . A manufacturing method of the raw magnesium alloy powder material according to  claim 1 , wherein
 0.5% to 4% by weight of a metal element selected from a group consisting of strontium (Sr), zirconium (Zr), scandium (Sc) and titanium (Ti) is contained and the balance is magnesium (Mg) substantially.   
     
     
         7 . A magnesium alloy with high proof stress provided by compacting and extruding the raw magnesium alloy powder material according to  claim 1 , characterized in that
 a magnesium particle constituting an alloy base has a maximum crystal grain diameter of 10 μm or less, and its tensile proof stress is 250 MPa or more at room temperature.   
     
     
         8 . The magnesium alloy with high proof stress according to  claim 7 , wherein
 the magnesium particle constituting the magnesium alloy base has a maximum crystal grain diameter of 5 μm or less, and   its tensile proof stress is 350 MPa or more at room temperature.   
     
     
         9 . The magnesium alloy with high proof stress according to  claim 7 , wherein
 at least one intermetallic compound selected from a group consisting of Mg 17 Al 12 , Al 2 Ca, Mg 2 Si, MgZn 2 , Al 3 Re (Re: rare-earth element), Al 11 Re 3 , and Al 6 Mn is precipitated and dispersed in the base of said magnesium alloy.   
     
     
         10 . A manufacturing method of a raw magnesium alloy powder material for miniaturizing a crystal grain diameter of a magnesium particle constituting a base of a starting material powder by performing a plastic working on the starting material powder, characterized in that
 a magnesium alloy powder having a fine intermetallic compound precipitated and dispersed by a heat treatment in a base is prepared as said starting material powder,   said plastic working is performed to provide work strains around said intermetallic compound by passing said starting material powder through a pair of rolls to make it undergo compressive deformation or shear deformation, and   said plastic working is repeated until the maximum size and minimum size of the powder become 10 mm or less and 0.1 mm or more, respectively, and the maximum crystal grain diameter of the magnesium particle constituting the base of the powder becomes 20 μm or less.   
     
     
         11 . The manufacturing method of the raw magnesium alloy powder material according to  claim 10 , wherein
 the step of preparing the magnesium alloy powder as said starting material powder comprises   a step of manufacturing a magnesium alloy ingot by casting,   a step of precipitating and dispersing a fine intermetallic compound in the base of the ingot by performing a solution treatment and then aging heat treatment for said magnesium alloy ingot, and   a step of obtaining the magnesium alloy powder from said ingot by machining.   
     
     
         12 . The manufacturing method of the raw magnesium alloy powder material according to  claim 11 , wherein
 the temperature of the starting material powder to be poured and the surface temperature of said roll to be in contact with the starting material powder are to be the temperature of said aging heat treatment or less at the time of said plastic working.   
     
     
         13 . The manufacturing method of the raw magnesium alloy powder material according to  claim 11 , wherein
 said magnesium alloy ingot contains 0.5 to 4% by weight of a metal element selected from a group consisting of strontium (Sr), zirconium (Zr), scandium (Sc) and titanium (Ti) and the balance of magnesium (Mg) substantially.   
     
     
         14 . A manufacturing method of a magnesium alloy with high proof stress comprising:
 a step of obtaining a compact by compacting the raw magnesium alloy powder material according to  claim 1  and filled in a die;   a step of heating said magnesium alloy powder compact to 150 to 450° C.; and   a step of manufacturing a magnesium alloy by extruding said magnesium alloy compact immediately after said heating step.   
     
     
         15 . The manufacturing method of the magnesium alloy with high proof stress according to  claim 14 , wherein
 a magnesium particle constituting the base of said magnesium alloy has a maximum crystal grain diameter of 10 μm or less, and   its tensile proof stress is 250 MPa or more at room temperature.   
     
     
         16 . The manufacturing method of the magnesium alloy with high proof stress according to  claim 14 , wherein
 said magnesium alloy compact is heated at 200 to 350° C.