Navigation Links
New magnetic-field-sensitive alloy could find use in novel micromechanical devices
Date:11/23/2011

Led by a group at the University of Maryland (UMd), a multi-institution team of researchers has combined modern materials research and an age-old metallurgy technique to produce an alloy that could be the basis for a new class of sensors and micromechanical devices controlled by magnetism.* The alloy, a combination of cobalt and iron, is notable, among other things, for not using rare-earth elements to achieve its properties. Materials scientists at the National Institute of Standards and Technology (NIST) contributed precision measurements of the alloy's structure and mechanical properties to the project.

The alloy exhibits a phenomenon called "giant magnetostriction," an amplified change in dimensions when placed in a sufficiently strong magnetic field. The effect is analogous to the more familiar piezoelectric effect that causes certain materials, like quartz, to compress under an electric field. They can be used in a variety of ways, including as sensitive magnetic field detectors and tiny actuators for micromechanical devices. The latter is particularly interesting to engineers because, unlike piezoelectrics, magnetostrictive elements require no wires and can be controlled by an external magnetic field source.

To find the best mixture of metals and processing, the team used a combinatorial screening technique, fabricating hundreds of tiny test cantilevers -- tiny, 10-millimeter-long, silicon beams looking like diving boards -- and coating them with a thin film of alloy, gradually varying the ratio of cobalt to iron across the array of cantilevers. They also used two different heat treatments, including, critically, one in which the alloy was heated to an annealing temperature and then suddenly quenched in water.

Quenching is a classic metallurgy technique to freeze a material's microstructure in a state that it normally only has when heated. In this case, measurements at NIST and the Stanford Synchrotron Radiation Lightsource (SSRL) showed that the best-performing alloy had a delicate hetereogenous, nanoscale structure in which cobalt-rich crystals were embedded throughout a different, iron-rich crystal structure. Magnetostriction was determined by measuring the amount by which the alloy bent the tiny silicon cantilever in a magnetic field, combined with delicate measurements at NIST to determine the stiffness of the cantilever.

The best annealed alloy showed a sizeable magnetostriction effect in magnetic fields as low as about 0.01 Tesla. (The earth's magnetic field generally ranges around roughly 0.000 045 T, and a typical ferrite refrigerator magnet might be about 0.7 T.)

The results, says team leader Ichiro Takeuchi of UMd, are lower than, but comparable to, the values for the best known magnetostrictive material, a rare-earth alloy called Tb-Dy-Fe** -- but with the advantage that the new alloy doesn't use the sometimes difficult to acquire rare earths. "Freezing in the heterogeneity by quenching is an old method in metallurgy, but our approach may be unique in thin films," he observes. "That's the beauty -- a nice, simple technique but you can get these large effects."

The quenched alloy might offer both size and processing advantages over more common piezoelectric microdevices, says NIST materials scientist Will Osborn. "Magnetorestriction devices are less developed than piezoelectrics, but they're becoming more interesting because the scale at which you can operate is smaller," he says. "Piezoelectrics are usually oxides, brittle and often lead-based, all of which is hard on manufacturing processes. These alloys are metal and much more compatible with the current generation of integrated device manufacturing. They're a good next-generation material for microelectromechanical machines."


'/>"/>
Contact: Michael Baum
baum@nist.gov
301-975-2763
National Institute of Standards and Technology (NIST)
Source:Eurekalert  

Related biology technology :

1. Re-Shaping the Future with Shape Memory Alloys - SMA Starter Kit
2. Mismatched alloys are a good match for thermoelectrics
3. Titanium and Aluminum Distributor, Trans World Alloys Relocates to Its Newly Built, State-of-the-Art Headquarters in Gardena, California
4. Ed Brennan - New C.O.O. of Trans World Alloys
5. The nanoscale secret to stronger alloys
6. Vaxfectin(R)-formulated Measles DNA Vaccine Could Address Unmet Need for Infants
7. Carbon molecule with a charge could be tomorrows semiconductor
8. New knowledge about thermoelectric materials could give better energy efficiency
9. A new material could act as a nanofridge for microchips
10. Could Database Software Help Cure Alzheimers and Save the Earth?
11. Cold atoms could replace hot gallium in focused ion beams
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
New magnetic-field-sensitive alloy could find use in novel micromechanical devices
(Date:5/23/2017)... , ... May 23, 2017 , ... A recent survey ... most troublesome and difficult to control weed in 12 categories of broadleaf crops, fruits ... 200 weed scientists across the U.S. and Canada participated in the 2016 survey, the ...
(Date:5/23/2017)... , ... May 22, 2017 , ... ... Photonics 2017 in San Diego, California, this August will feature high-level speakers ... and autonomous vehicles. , SPIE Optics and Photonics, the largest multidisciplinary optical sciences ...
(Date:5/23/2017)... ... 2017 , ... Bacterial biofilms, surface adherent communities of bacteria that are encased ... food poisoning and catheter infections to gum disease and the rejection of medical implants. ... dollars per year, there is currently a paucity of means for preventing their formation ...
(Date:5/22/2017)... ... May 22, 2017 , ... Baltimore biotech firm, PathSensors, ... Biohealth community in developing and issuing recommendations to grow Maryland's biohealth industry and ... by 2023. , The recommendations are contained in a report ...
Breaking Biology Technology:
(Date:3/29/2017)... -- higi, the health IT company that operates the largest ... , today announced a Series B investment from BlueCross ... new investment and acquisition accelerates higi,s strategy to create ... health activities through the collection and workflow integration of ... and secures data today on behalf of over 36 ...
(Date:3/24/2017)... 2017 Research and Markets has announced the ... & Trends - Industry Forecast to 2025" report to their ... The Global ... CAGR of around 15.1% over the next decade to reach approximately ... the market estimates and forecasts for all the given segments on ...
(Date:3/22/2017)... March 21, 2017 Optimove , ... by retailers such as 1-800-Flowers and AdoreMe, today ... Recommendations and Replenishment. Using Optimove,s machine learning algorithms, ... product and replenishment recommendations to their customers based ... predictions of customer intent drawn from a complex ...
Breaking Biology News(10 mins):