When a newspaper announced the attempted theft of a new metal formulation by a Chinese student at Iowa State University, I was inspired to learn more about what was involved. I was "boggled" on many scores. Bill Gertz's item in Washington Times on 5 August mentioned the name Terfenol-D, a magnetostrictive metal, and the producer of that material, Etrema Products Inc. of Ames, Iowa. Using the Google search engine and entering the metal name and manufacturer, I was presented 335 documents within 0.41 seconds that would take weeks to read but described most of what any reasonable person could want to know about this topic.
Boggle #1: The Internet has grown in a dozen years to become a greater engine for discovery than all libraries and other stores of knowledge have cumulatively provided in all of human history. Access to knowledge, to acquire instant response to amorphously defined inquiries that are specific but related only in associative terms, is a marvel that defies adequate, descriptive appreciation. Suffice it to say that the computer beats going to the library on a hot August afternoon and remembering how to use the Dewey Decimal System. It is important for the younger half of America's population, under age 26, to appreciate this free Internet resource and for the older half of the citizenry to learn its use with skill and confidence. All should say a thankful prayer for computers. Paying homage to the Internet is akin to thanking parents for assisting children to shine the light of understanding on the darkness of ignorance. A lesson here is to use that bright light, the Internet, to illuminate your world with appreciation for being the powerful tool it is.
Boggle #2: learning what Terfenol is and can do. About twelve years ago the U.S. Navy funded development of a process for an alloy of rare earth metals terbium (0.3) and dysprosium (0.7) with iron (1.92). Because this "smart material" is magnetostrictive, the physical property discovered by English physicist James Joule in 1842, it reacts mechanically by increasing in size, the "jump effect," when stimulated by small magnetic fields. Navy can now drive underwater (acoustic) sonars with greater power and efficiency. Very clever and costly to develop, but there are many, startling commercial uses for Terfenol. The world of smart materials is now a $1 billion industry with magnetostrictive products capturing 10% of the market.
Terfenol is made in a melt process that grows crystalline boules, similar to how electronic semiconductor materials are grown before slicing into wafers. It is a brittle alloy and exhibits Young's modulus of 25-35 GPA, tensile strength of 28 Mpa and compressive strength of 700 Mpa. Its magnetostrictive nature, compared to piezoelectric ceramic materials that also "jump," is ten to a hundred times greater (linear strain up to 1200 ppm), is repeatable without degradation or fatigue, actuates in microseconds, works on a continuous basis, with a few volts supplied by a switch on an electromagnet couples the field with 75% efficiency, operates over a thermal range of -50 to +200¿C, and operates under 10,000 psi pressure. A 6 millimeter (mm) diameter rod one meter long can elongate 1 to 2 mm and exert 100 lb dynamic force and large diameters over 50,000 lb. It is used in rods typically 11 to 30 mm diameter, but is available in sizes as small as 1 mm square and as large as 65 mm round; the quantity cost is about $1 a gram, $450 a pound.
Boggle #3: price. As a physical chemistry lab project in engineering school, I had the misfortune to grind a 55 gallon drum of rare earth ore, acid digest it, and precipitate not enough rare earth salts to darken a filter paper, much less see any metal. So while I personally am convinced there is not enough terbium and dysprosium in the universe to make Terfenol, the maker somehow manages.
That internet search revealed 29 worldwide manufacturers of magnetostrictive materials, 27 being piezo-ceramic providers. The other 2 are alloy providers, Etrema and, would you believe, Gansu Tianxing Rare Earth Functional Materials Co. Ltd., reported employer of that Chinese student from Iowa that the FBI still is seeking. Users of pirated alloy violate U.S. and foreign patents and will not make equivalent performance devices.
This story leads to a logical conclusion for business interests. Some imagination shows that Terfenol can be used in many industrial and consumer applications. Actuators are used to stimulate oil well recoveries; make acoustic speakers, electricity generators, ultrasonic vibrator cleaning machines, destroy pathogens in water; or whatever your creativity can divine. Etrema, subsidiary of Edge Technologies Inc, with only 32 employees has too many opportunities to do everything itself so is interested in product and application developments with partners. Call Etrema representatives Tim Drake (816-246-0566) to discuss your ideas in the oil and gas sector, Tony Melone (630-236-8474) to talk about machining, foundry, casting, or water remediation systems, or Todd Kreamer, Marketing Director (515-296-8030), on general questions. Boggle #4 can be your dream.