Galfenol
Encyclopedia
In materials science
, galfenol is the general term for an alloy
of iron
and gallium
. The name was first given to iron-gallium alloys by United States Navy researchers in 1998 when they discovered that adding gallium to iron could amplify iron's magnetostrictive effect up to tenfold. Galfenol is of interest to sonar
researchers because magnetostrictor materials are used to detect sound, and amplifying the magnetostrictive effect could lead to better sensitivity of sonar detectors.
In 2009, scientists from Virginia Polytechnic Institute and State University
, and National Institute of Standards and Technology
(NIST) used neutron
beams to determine the structure
of galfenol. They determined that the addition of gallium changes the lattice structure of the iron atoms from regular cubic cells to one in which the faces of some of the cells become slightly rectangular. The elongated cells tend to clump together in the alloy, forming localized clumps within the material. These clumps have been likened by Peter Gehring of the NIST Center for Neutron Research to "something like raisins within a cake".
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...
, galfenol is the general term for an alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
and gallium
Gallium
Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
. The name was first given to iron-gallium alloys by United States Navy researchers in 1998 when they discovered that adding gallium to iron could amplify iron's magnetostrictive effect up to tenfold. Galfenol is of interest to sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
researchers because magnetostrictor materials are used to detect sound, and amplifying the magnetostrictive effect could lead to better sensitivity of sonar detectors.
In 2009, scientists from Virginia Polytechnic Institute and State University
Virginia Polytechnic Institute and State University
Virginia Polytechnic Institute and State University, popularly known as Virginia Tech , is a public land-grant university with the main campus in Blacksburg, Virginia with other research and educational centers throughout the Commonwealth of Virginia, United States, and internationally.Founded in...
, and National Institute of Standards and Technology
National Institute of Standards and Technology
The National Institute of Standards and Technology , known between 1901 and 1988 as the National Bureau of Standards , is a measurement standards laboratory, otherwise known as a National Metrological Institute , which is a non-regulatory agency of the United States Department of Commerce...
(NIST) used neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
beams to determine the structure
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
of galfenol. They determined that the addition of gallium changes the lattice structure of the iron atoms from regular cubic cells to one in which the faces of some of the cells become slightly rectangular. The elongated cells tend to clump together in the alloy, forming localized clumps within the material. These clumps have been likened by Peter Gehring of the NIST Center for Neutron Research to "something like raisins within a cake".
External links
- http://www.aerosmart.umd.edu/TechPubs/Kellogg_2003_Dissertation.pdf Development and modeling of iron-gallium alloy, Rick A. Kellogg
- http://hdl.handle.net/1903/3951 Characterization and Modeling of the Magnetomechanical Behavior of Iron-Gallium Alloys, Jayasimha Atulasimha
- http://hdl.handle.net/1903/8874 Characterization of Bending Magnetostriction in Iron-Gallium Alloys for Nanowire Sensor Applications, Patrick Downey
- http://hdl.handle.net/1903/9310 Quasi-static Characterization and Modeling of the Bending Behavior of Single Crystal GALFENOL for Magnetostrictive Sensors and Actuators, Supratik Datta