Aluminum alloy having improved oxidation resistance, corrosion resistance, or fatigue resistance, and die-cast material and extruded material prepared by using the aluminum alloy

Abstract

Provided are an aluminum (Al) alloy prepared environment friendly and having excellent oxidation resistance properties, and a method of preparing the Al alloy. An oxidation-resistant Al alloy according to an embodiment of the present invention is casted by adding a magnesium (Mg) master alloy, in which a calcium (Ca)-based compound is distributed in an Mg matrix, into molten Al. An Al matrix includes the Ca-based compound. The Al alloy has superior oxidation resistance to a corresponding Al alloy not including the Ca-based compound.

1 . An aluminum (Al) alloy casted by adding a magnesium (Mg) master alloy, in which a calcium (Ca)-based compound is distributed in an Mg matrix, into molten Al,
 wherein an Al matrix includes the Ca-based compound, and   wherein the Al alloy has superior oxidation resistance, corrosion resistance against salt water, or fatigue resistance to a corresponding Al alloy not including the Ca-based compound.   
     
     
         2 . The Al alloy of  claim 1 , wherein the Ca-based compound comprises at least one of an Mg—Ca compound, an Al—Ca compound, and an Mg—Al—Ca compound, and wherein the Mg—Ca compound comprises Mg 2 Ca, the Al—Ca compound comprises at least one of Al 2 Ca and Al 4 Ca, and the Mg—Al—Ca compound comprises (Mg,Al) 2 Ca. 
     
     
         3 . The Al alloy of  claim 1 , wherein the Mg master alloy is prepared by adding a Ca-based additive into molten parent material including pure Mg, or an Mg alloy including Al, as a parent material. 
     
     
         4 . The Al alloy of  claim 1 , wherein the Ca-based compound is formed by dispersively adding a Ca-based additive onto a surface of an upper part of molten Mg, and then exhausting at least a portion of the Ca-based additive in the molten Mg. 
     
     
         5 . The Al alloy of  claim 4 , wherein the Ca-based compound is formed by exhausting the Ca-based additive in the molten Mg in such a way that the Ca-based additive does not substantially remain in the Mg master alloy. 
     
     
         6 . The Al alloy of  claim 5 , wherein the upper part of the molten Mg is stirred and the stirring is performed at the upper part which is within 20% of a total depth of the molten Mg. 
     
     
         7 . The Al alloy of  claim 4 , wherein the Ca-based additive comprises at least one of calcium oxide (CaO), calcium cyanide (CaCN 2 ), and calcium carbide (CaC 2 ). 
     
     
         8 . The Al alloy of  claim 4 , wherein at least a portion of the Ca-based additive is exhausted in molten parent material, and
 wherein the Ca-based compound is formed due to reaction between Ca supplied from the Ca-based additive and Mg or Al of the parent material.   
     
     
         9 . The Al alloy of  claim 1 , wherein the Mg master alloy is added by 0.0001 parts by weight to 30 parts by weight based on 100 parts by weight of Al, and
 wherein the Ca-based additive is added by 0.0001 parts by weight to 30 parts by weight based on 100 parts by weight of the parent material.   
     
     
         10 . The Al alloy of  claim 1 , wherein Mg is dissolved in the Al matrix within a range of 0.1 wt % to 15 wt %. 
     
     
         11 . The Al alloy of  claim 1 , wherein, if a content of the Ca-based compound is increased, a weight gain of the Ca-based compound due to oxidation under the same oxidation condition is reduced. 
     
     
         12 . The Al alloy of  claim 1 , wherein the superior fatigue resistance refers to a larger cycle number leading fatigue fracture if a cyclic load is applied at a predetermined frequency under stress conditions of 40% to 80% of a tensile strength. 
     
     
         13 . An aluminum (Al) alloy extruded material prepared by extruding the Al alloy of  claim 1 , and having a higher strength in comparison to an Al alloy extruded material prepared under the same condition except that the Ca-based compound is not included. 
     
     
         14 . An aluminum (Al) alloy die-cast material prepared by using molten metal of the Al alloy of  claim 1 , and having a higher strength in comparison to an Al alloy die-cast material prepared under the same condition except that the Ca-based compound is not included. 
     
     
         15 . A method of preparing an aluminum (Al) alloy extruded material, the method comprising:
 preparing molten Al including magnesium (Mg);   preparing an Al alloy by casting the molten Al; and   extruding the Al alloy,   wherein the molten Al is prepared by melting Al together with an Mg master alloy in which a calcium (Ca)-based compound combined with at least one of Mg and Al is included in an Mg matrix.   
     
     
         16 . The method of  claim 4 - 415 , further comprising performing heat treatment on the Al alloy extruded material after the Al alloy is extruded. 
     
     
         17 . A method of preparing an aluminum (Al) alloy die-cast material, the method comprising:
 preparing molten Al including magnesium (Mg); and   casting the molten Al; and   wherein the molten Al is prepared by melting Al together with an Mg master alloy in which a calcium (Ca)-based compound combined with at least one of Mg and Al is included in an Mg matrix.