Aluminum alloy having visible grains and aluminum alloy colored by double anodization

Abstract

Embodiments relate to a type of aluminum alloy with grains visible to naked eyes. The aluminum alloy may have an average grain size of at least 100 μm. The aluminum alloy can be produced by a process such as casting, extrusion, solutionizing, aging, and etching. The solutionizing causes recrystallization of aluminum and causes grains of the aluminum to grow. Compared with the solutionizing, the aging is performed at lower temperature but enhances strength of the aluminum alloy. The etching makes grain boundaries of the aluminum alloy more prominent, rendering the grains of the aluminum alloy visible to a naked human eye.

What is claimed is: 
     
         1 . A method for processing an aluminum alloy, the method comprising:
 reducing iron concentration in the aluminum alloy to obtain a concentration of iron below a threshold value;   heating the aluminum alloy at a first temperature for a first period of time, wherein the heating causes recrystallization of aluminum;   aging the aluminum alloy at a second temperature for a second period of time, the second temperature lower than the first temperature, wherein the aging enhances strength of the aluminum alloy; and   rendering grain boundaries of the aluminum alloy visible to a human eye.   
     
     
         2 . The method of  claim 1 , further comprising:
 growing average grain size of the aluminum alloy to at least 100 μm.   
     
     
         3 . The method of  claim 2 , wherein the growing of the average grain size is performed during a solutionizing process. 
     
     
         4 . The method of  claim 3 , wherein the solutionizing temperature is higher than 480° C. 
     
     
         5 . The method of  claim 3 , wherein the aging is performed at a temperature lower than a temperature at which the solutionizing process is performed. 
     
     
         6 . The method of  claim 1 , wherein the iron concentration is reduced during a casting process. 
     
     
         7 . The method of  claim 1 , further comprising reducing one or more of zirconium, scandium, titanium and carbide. 
     
     
         8 . The method of  claim 1 , wherein rendering of the grain boundaries visible comprises etching grain boundaries of the aluminum alloy 
     
     
         9 . The method of  claim 9 , wherein the etching is performed using one selected from a group comprising Caustic Soda (NaOH), Hydrofluoric Acid (HF), and Iron III Chloride (FeCl 3 ), or any combination thereof. 
     
     
         10 . The method of  claim 1 , wherein the rendering of the grain boundaries visible comprises precipitating anodic phases on the grain boundaries. 
     
     
         11 . The method of  claim 1 , further comprising:
 casting the aluminum alloy using a direct chill cast process; and   extruding the casted aluminum alloy to a predetermined shape.   
     
     
         12 . A method for anodizing an aluminum alloy, the method comprising:
 etching grain boundaries of the aluminum alloy;   anodizing the aluminum alloy with a first color, wherein the anodizing causes grain boundaries and grains of the aluminum alloy to be coated with an anodic oxide layer of the first color;   removing the anodic oxide layer of the first color from the grains of the aluminum alloy; and   anodizing the aluminum alloy with a second color, wherein the anodizing causes the grains of the aluminum alloy to be coated with an anodic oxide layer of the second color.   
     
     
         13 . The method of  claim 12 , further comprising performing sand blasting after etching the grain boundaries. 
     
     
         14 . The method of  claim 12 , wherein the removing of the anodic oxide layer is performed by lapping. 
     
     
         15 . An aluminum alloy is produced by a process, the process comprising:
 reducing iron concentration in the aluminum alloy to obtain a concentration of iron below a threshold value;   heating the aluminum alloy at a first temperature for a first period of time, wherein the heating causes recrystallization of aluminum;   aging the aluminum alloy at a second temperature for a second period of time, the second temperature lower than the first temperature, wherein the aging enhances strength of the aluminum alloy; and   rendering grain boundaries of the aluminum alloy visible to a human eye.   
     
     
         16 . The aluminum alloy of  claim 15 , further comprising:
 growing average grain size of the aluminum alloy to at least 100 μm.   
     
     
         17 . The aluminum alloy of  claim 16 , wherein the growing of the average grain size is performed during a solutionizing process. 
     
     
         18 . The aluminum alloy of  claim 17 , wherein the solutionizing temperature is higher than 480° C. 
     
     
         19 . The aluminum alloy of  claim 15 , wherein the aging is performed at a temperature lower than a temperature at which the solutionizing process is performed. 
     
     
         20 . An aluminum alloy is anodized by a process, the process comprising:
 etching grain boundaries of the aluminum alloy;   anodizing the aluminum alloy with a first color, wherein the anodizing causes grain boundaries and grains of the aluminum alloy to be coated with an anodic oxide layer of the first color;   removing the anodic oxide layer of the first color from the grains of the aluminum alloy; and   anodizing the aluminum alloy with a second color, wherein the anodizing causes the grains of the aluminum alloy to be coated with an anodic oxide layer of the second color.