Patent ID: 8163113

Claim:
A method for increasing the room temperature formability of an aluminum alloy article comprising aluminum as a major constituent and chromium as an alloying element in a total amount in the range of about 0.05% to about 0.35% by weight, and further comprising iron as an impurity; the method comprising: heating the alloy to a first temperature at which the chromium and the iron are substantially dissolved in a matrix of aluminum; quenching the aluminum alloy to below about 35° C. in a first quench to retain the chromium and the iron in solution in the aluminum matrix; heating the aluminum alloy to a second temperature, lower than the first temperature to precipitate a portion of the chromium content from the matrix of aluminum as particles of a chromium-containing and aluminum-containing intermetallic compound, the remainder of the chromium content being retained in solid solution in the aluminum matrix, and the iron continuing to be maintained substantially in solid solution in the matrix of aluminum; quenching the aluminum alloy to below about 35° C. in a second quench to retain the chromium and the iron in solution in the aluminum matrix; heating the aluminum alloy to a third temperature, lower than the second temperature, to cause a substantial portion of the iron content to be precipitated from the matrix of aluminum as particles of an iron-containing and aluminum-containing intermetallic compound, the remainder of the chromium continuing to be maintained substantially in solid solution in the matrix of aluminum; and cooling the aluminum alloy to a temperature less than about 35° C.