Abstract: A free machining aluminum alloy contains an effective amount of one or more high melting point constituents that provide enhanced machining capability. The high melting point constituents occupy from about 0.1 to about 3.0 volume percent of the aluminum alloy. The constituents can be any material that is essentially insoluble in the aluminum alloy matrix so as to form a discontinuity and one that will resist deformation during machining to enhance the formation of voids between the matrix and the free machining constituents. The constituents include elements, nitrides, oxides, borides, carbides, silicides, aluminides and combinations thereof that have a high melting point and high strength and low solubility in aluminum at the elevated temperature so that the constituents resist deformation during the machining operation. The free machining aluminum alloy can be formed as a workpiece and subjected to any machining operation.

Abstract: An aluminum alloy composition includes controlled amounts of iron, manganese, zinc, zirconium, vanadium, and titanium to effectively inhibit grain growth during exposure to elevated temperatures while maintaining extrudability and corrosion resistance. The composition is especially adapted for use as micro-multivoid tubing for brazed heat exchanger applications and has a post-braze grain structure that is more resistant to intergranular corrosion so as to reduce or eliminate heat exchanger failures during service.

Abstract: An aluminum alloy article containing the alloying amounts of iron, silicon, manganese, titanium, and zinc has controlled levels of iron and manganese to produce an alloy article that combines excellent corrosion resistant with good formability. The alloy article composition employs a controlled ratio of manganese to iron and controlled total amounts of iron and manganese to form intermetallic compounds in the final alloy article. The electrolytic potential of the intermetallic compounds match the aluminum matrix of the article to minimize corrosion. The levels of iron and manganese are controlled so that the intermetallic compounds are present in a volume fraction that allows the alloy article to be easily formed. The aluminum alloy composition is especially adapted for extrusion processes, and tubing that are used in heat exchanger applications.

Abstract: A free machining aluminum alloy contains an effective amount of one or more high melting point constituents that provide enhanced machining capability. The high melting point constituents occupy from about 0.1 to about 3.0 volume percent of the aluminum alloy. The constituents can be any material that is essentially insoluble in the aluminum alloy matrix so as to form a discontinuity and one that will resist deformation during machining to enhance the formation of voids between the matrix and the free machining constituents. The constituents include elements, nitrides, oxides, borides, carbides, silicides, aluminides and combinations thereof that have a high melting point and high strength and low solubility in aluminum at the elevated temperature so that the constituents resist deformation during the machining operation. The free machining aluminum alloy can be formed as a workpiece and subjected to any machining operation.

Abstract: One free machining aluminum alloy includes bismuth as a free machining elemental constituent that functions as a discontinuity in the aluminum alloy matrix rather than a low melting point compound. Using bismuth in weight percents of the total composition ranging between 0.1% and 3.0% improves both machinability and mechanical properties. The bismuth can act as a substitute for another free machining constituent in a free machining aluminum alloy or can be added to an aluminum alloy to improve its machinability. Another free machining aluminum alloy has bismuth and tin as free machining constituents for improved machining. When using bismuth and tin, the bismuth ranges between 0.1 and 3.0% by weight and the tin ranges between 0.1 and 1.5% by weight.