Control of aluminum alloy microstructure for improved corrosion resistance and bonding performance

Abstract

Described are aluminum alloy products that generally have a microstructure and composition that resists corrosion. This corrosion resistance, in turn, allows the aluminum alloy products to exhibit favorable bond durability performance, such as when adhesively bonded to another product. The corrosion resistance can be achieved by controlling the composition of the aluminum alloy, including the presence and/or concentration of certain intermetallic particles, such as α-phase intermetallic particles and β-phase intermetallic particles.

1 . An aluminum alloy product comprising:
 a 6xxx series aluminum alloy, wherein a total concentration of α-phase-stabilizing alloying elements in the 6xxx series aluminum alloy is greater than or about 0.2 wt. %, or wherein a ratio of the total concentration of α-phase-stabilizing alloying elements to an amount of excess silicon in the 6xxx series aluminum alloy is greater than or about 1.0, or wherein a ratio of an amount of magnesium in the 6xxx series aluminum alloy to an amount of silicon in the 6xxx series aluminum alloy is less than or about 4.0;   wherein the 6xxx series aluminum alloy includes β-phase intermetallic particles and α-phase intermetallic particles; and   wherein a weight percent ratio of the α-phase intermetallic particles to the β-phase intermetallic particles in the aluminum alloy product is greater than 2.0.   
     
     
         2 . The aluminum alloy product of  claim 1 , exhibiting a bond durability of from 30 cycles to 65 cycles or more according to an ASTM D3762 standard test or a FLTM BV 101-07 standard test. 
     
     
         3 . The aluminum alloy product of  claim 1 , wherein the 6xxx series aluminum alloy comprises up to 0.25 wt. % titanium carbide. 
     
     
         4 . The aluminum alloy product of  claim 1 , wherein the α-phase-stabilizing alloying elements comprise one or more of copper, chromium, manganese, zirconium or vanadium. 
     
     
         5 . The aluminum alloy product of  claim 1 , wherein the total concentration of α-phase-stabilizing alloying elements is less than or about 2 wt. %. 
     
     
         6 . The aluminum alloy product of  claim 1 , wherein the ratio of the total concentration of α-phase-stabilizing alloying elements to the amount of excess silicon in the 6xxx series aluminum alloy is less than or about 3. 
     
     
         7 . The aluminum alloy product of  claim 1 , wherein the 6xxx series aluminum alloy comprises:
 up to 1.8 wt. % silicon;   up to 1.8 wt. % iron;   up to 1.5 wt. % copper;   up to 0.5 wt. % manganese;   from 0.2 wt. % to 3.0 wt. % magnesium;   up to 0.25 wt. % titanium;   up to 1.5 wt. % zinc;   up to 1 wt. % nickel;   up to 0.25 wt. % vanadium;   up to 0.25 wt. % zirconium;   up to 0.5 wt. % chromium; and   aluminum.   
     
     
         8 . (canceled) 
     
     
         9 . The aluminum alloy product of  claim 1 , wherein an excess silicon amount in the 6xxx series aluminum alloy is greater than or about 0.1 wt. %, wherein an excess silicon amount in the 6xxx series aluminum alloy is less than or about 1.4%, wherein the 6xxx series aluminum alloy is substantially free of boron, or wherein a concentration of a carbide grain refiner in the 6xxx series aluminum alloy is up to 10 parts per million. 
     
     
         10 .- 12 . (canceled) 
     
     
         13 . The aluminum alloy product of  claim 1 , wherein a ratio of the total concentration of α-phase-stabilizing stabilizing elements to iron in the α-phase intermetallic particles is greater than 0.5. 
     
     
         14 . The aluminum alloy product of  claim 1 , wherein the β-phase intermetallic particles exhibit an aspect ratio greater than 2, and wherein the α-phase intermetallic particles exhibit an aspect ratio of from 1 to 1.5. 
     
     
         15 . The aluminum alloy product of  claim 1 , wherein the β-phase intermetallic particles comprise aluminum, iron, and silicon, and wherein the α-phase intermetallic particles comprise aluminum, silicon, and one or more of iron, manganese, or chromium. 
     
     
         16 . The aluminum alloy product of  claim 1 , wherein the weight percent ratio of the α-phase intermetallic particles to the β-phase intermetallic particles in the aluminum alloy product is determined by a process comprising phase characterization using energy dispersive x-ray spectroscopy (EDXS) composition analysis. 
     
     
         17 . The aluminum alloy product of  claim 1 , wherein a corrosion potential of the β-phase intermetallic particles is greater than that of an aluminum alloy matrix supporting the β-phase intermetallic particles. 
     
     
         18 . The aluminum alloy product of  claim 1 , wherein a corrosion potential of the β-phase intermetallic particles is greater than that of the α-phase intermetallic particles. 
     
     
         19 . The aluminum alloy product of  claim 1 , wherein the aluminum alloy product exhibits reduced corrosion potential as compared to a comparable aluminum alloy product comprising:
 a comparable 6xxx series aluminum alloy having a total concentration of α-phase-stabilizing alloying elements of less than 0.5 wt. %;   β-phase intermetallic particles; and   α-phase intermetallic particles, wherein a comparable weight percent ratio of the α-phase intermetallic particles to the β-phase intermetallic particles in the comparable aluminum alloy is less than 1.   
     
     
         20 . A joined aluminum alloy product, comprising:
 the aluminum alloy product of  claim 1 ;   a second product; and   an adhesive between the aluminum alloy product and the second product, the adhesive joining the aluminum alloy product and the second product.   
     
     
         21 . The joined aluminum alloy product of  claim 20 , exhibiting a bond durability of from 30 cycles to 65 cycles or more according to an ASTM D3762 standard test or a FLTM BV 101-07 standard test. 
     
     
         22 . The joined aluminum alloy product of  claim 20 , further comprising an adhesion promoter on a surface of the aluminum alloy product or between the aluminum alloy product and the adhesive. 
     
     
         23 . The joined aluminum alloy product of  claim 20 , wherein at least a portion of a surface of the aluminum alloy product is chemically modified or pretreated, or wherein at least a portion of a surface of the aluminum alloy product includes a self-assembled monolayer of one or more phosphorus containing organic acids. 
     
     
         24 . (canceled) 
     
     
         25 . A method comprising:
 preparing an aluminum alloy product, the aluminum alloy product comprising:
 a 6xxx series aluminum alloy, wherein a total concentration of α-phase-stabilizing alloying elements in the 6xxx series aluminum alloy is greater than or about 0.2 wt. %, or wherein a ratio of the total concentration of α-phase-stabilizing alloying elements to an amount of excess silicon in the 6xxx series aluminum alloy is greater than or about 1.0, or wherein a ratio of an amount of magnesium in the 6xxx series aluminum alloy to an amount of silicon in the 6xxx series aluminum alloy is less than or about 4.0; 
 β-phase intermetallic particles; and 
 α-phase intermetallic particles; and 
   subjecting the aluminum alloy product to processing conditions that modify or control a weight percent ratio of the α-phase intermetallic particles to the β-phase intermetallic particles in the aluminum alloy product to be greater than 2.   
     
     
         26 .- 27 . (canceled)