Aluminum Bronzes

Overview

Aluminum bronzes are used for their combination of high strength, excellent corrosion and wear resistance. Aluminum bronze alloys typically contain 9-12% aluminum and up to 6% iron and nickel. Alloys in these composition limits are hardened by a combination of solid solution strengthening, cold work, and precipitation of an iron rich phase. High aluminum alloys are quenched and tempered. Aluminum bronzes are used in marine hardware, shafts and pump and valve components for handling seawater, sour mine waters, nonoxidizing acids, and industrial process fluids. They are also used in applications such as heavy duty sleeve bearings, and machine tool ways. They are designated by UNS C60800 through C64210. Aluminum bronze castings have exceptional corrosion resistance, high strength, toughness and wear resistance and good casting and welding characteristics. Aluminum bronze castings are designated as UNS C95200 to C95900.

The microstructure of the aluminum bronzes with less than 11% aluminum consist of alpha solid solution and the iron and nickel rich kappa phase. The kappa phase absorbs aluminum from the alpha solid solution preventing the formation of the beta phase unless the aluminum content is above 11%. The kappa phase increases the mechanical strength of the aluminum bronzes, with no decrease in ductility. The decrease in ductility of the aluminum bronzes occurs when the beta phase forms. The beta phase is harder and more brittle than the alpha phase. Beta is formed if the material is quenched or fast cooled, which then transforms into a hard, acicular martensite structure. Tempering the martensite results in a structure of alpha with kappa precipitates. The tempered structure is very desirable, it has high strength and hardness. The slow cooled, as cast structures consist of alpha and kappa phases. Kappa is present in the lamellar form and finely divided in all the alpha areas. The addition of iron and nickel also suppress the formation of the gamma double prime phase which has deleterious effects on the properties of aluminum copper alloys.

NOTE: The file size of the Larger and Largest View of the Micrographs are substantially larger than the thumbnail shown. The Larger View images range in size from 11K to 120K depending on the image. The Largest View images range in size from 125K to almost 500K.

Nominal Composition: Cu 90.83, Al 6.5, Fe 2.4, Sn 0.27 Larger View of Micrograph Largest View of Micrograph	Alloy Family:	Aluminum bronzes
	Product Form:	Plate
	Processing:	Hot rolled
	Etchant:
	Scale Line Length:	~ 125Microns
	Alloy:	C61300
	Temper:
	Material:	Aluminum bronze, 6-7.5 Al
	Source:	University of Florida