Dispersion hardenable Al-Ni-Mn casting alloys for automotive and aerospace structural components

Abstract

An aluminum casting alloy includes at least about 0.5 wt % Ni and 1-3 wt % Mn. It further includes zirconium or scandium for precipitation hardening during T 5 heat treatment.

We claim:  
     
         1 . An aluminum alloy wherein Ni is the most abundant alloying ingredient.  
     
     
         2 . An aluminum alloy, according to  claim 1 , wherein the concentration of Ni is about 4%.  
     
     
         3 . An aluminum alloy, according to  claim 1 , wherein Mn is the second most abundant alloying ingredient.  
     
     
         4 . An aluminum alloy, according to  claim 3 , wherein the concentration of Ni is about 4% and the concentration of Mn is about 2%.  
     
     
         5 . An aluminum casting alloy comprising: 
 about 0.5-6 wt % Ni,    about 1-3 wt % Mn, and    at least one element for precipitation hardening during artificial ageing.    
     
     
         6 . An aluminum casting alloy, according to  claim 5 , wherein the concentration of Ni is about 2-5 wt %.  
     
     
         7 . An aluminum casting alloy, according to  claim 6 , wherein the concentration of Ni is about 4 wt %.  
     
     
         8 . An aluminum casting alloy, according to  claim 5 , wherein the concentration of Mn is about 1.5-2.5 wt %.  
     
     
         9 . An aluminum casting alloy, according to  claim 5 , wherein the concentration of Mn is about 2 wt %.  
     
     
         10 . An aluminum casting alloy, according to  claim 5 , wherein the at least one element for precipitation hardening includes Sc.  
     
     
         11 . An aluminum casting alloy, according to  claim 10 , wherein the concentration of Sc is up to about 0.3 wt %.  
     
     
         12 . An aluminum casting alloy, according to  claim 5 , wherein the at least one element for precipitation hardening includes Zr.  
     
     
         13 . An aluminum casting alloy, according to  claim 12 , wherein the concentration of Zr is up to about 1 wt %.  
     
     
         14 . An aluminum casting alloy, according to  claim 12 , wherein the concentration of Zr is about 0.6%.  
     
     
         15 . An aluminum alloy casting comprising: 
 about 0.5-6 wt % Ni,    about 1-3 wt % Mn, and    at least one element for precipitation hardening,    a microstructure of the casting comprising aluminum dendrites in a matrix comprised of a eutectic of aluminum versus an AlNiMn intermetallic compound, and a relatively fine dispersion comprised of the at least one element for precipitation hardening, at least some of the dispersion disposed in the aluminum dendrites.    
     
     
         16 . An aluminum alloy casting, according to  claim 15 , wherein the at least one element for precipitation hardening includes Sc.  
     
     
         17 . An aluminum alloy casting, according to  claim 16 , wherein the concentration of Sc is less than about 1 wt %.  
     
     
         18 . An aluminum alloy casting, according to  claim 17 , wherein the concentration of Sc is about 0.3 wt %.  
     
     
         19 . An aluminum alloy casting, according to  claim 15 , wherein the at least one element for precipitation hardening includes Zr.  
     
     
         20 . An aluminum alloy casting, according to  claim 19 , wherein the concentration of Zr is less than about 1 wt %.  
     
     
         21 . An aluminum alloy casting, according to  claim 20 , wherein the concentration of Zr is about 0.6 wt %.  
     
     
         22 . An aluminum alloy casting, according to  claim 15 , wherein the aluminum alloy casting is a structural component of an aerospace product.  
     
     
         23 . An aluminum alloy casting, according to  claim 15 , wherein the aluminum alloy casting is a structural component of a motor vehicle product.  
     
     
         24 . A method of making an aluminum alloy casting, the method comprising: 
 preparing a molten aluminum alloy comprising 0.5-6 wt % Ni, 1-3 wt % Mn, Zr in a range from about 0.3-1 wt %;    heating the molten aluminum alloy to a temperature of at least above the liquidus temperature;    casting the molten aluminum alloy in a mold;    artificially ageing the casting.    
     
     
         25 . A method, according to  claim 24 , wherein a concentration of the Zr is about 0.6 wt % and the temperature is at least about 825 C.  
     
     
         26 . A method, according to  claim 24 , wherein a concentration of the Zr is about 0.7 wt % and the temperature is at least about 850 C.  
     
     
         27 . A method, according to  claim 24 , wherein a concentration of the Zr is about 0.8 wt % and the temperature is at least about 875 C.  
     
     
         28 . A method, according to  claim 24 , wherein a concentration of the Zr is about 0.9 wt % and the temperature is at least about 900 C.  
     
     
         29 . A method, according to  claim 24 , wherein a concentration of the Zr is about 1 wt % and the temperature is at least about 925 C.  
     
     
         30 . A method, according to  claim 24 , wherein the molten aluminum alloy further includes at least one grain refiner.  
     
     
         31 . A method, according to  claim 30 , wherein the at least one grain refiner includes Ti, TiB2, and TiC.  
     
     
         32 . A method, according to  claim 31 , wherein the concentration of Ti is about 0.15 wt %.  
     
     
         33 . A method, according to  claim 24 , wherein the step of artificially ageing the casting comprises maintaining a temperature of the casting at about 400 C for about 20 hours.  
     
     
         34 . A method, according to  claim 24 , wherein the step of artificially ageing the casting comprises maintaining a temperature of the casting at about 330 C for about 3 hours and then at about 450 C for about 2 hours.  
     
     
         35 . A method, according to  claim 24 , wherein the step of casting the alloy is at least one of high pressure die casting, permanent mold casting, dry sand casting, green sand casting, investment casting and other shaped casting processes.