New Generation of Lightweight, High-Strength Parts

New lightweight, high-strength magnesium sheet technology has been developed by nanoMAG LLC, a subsidiary of Thixomat Inc., Ann Arbor, Mich., the developer of the Thixomolding injection molding process which converts magnesium alloys into precision parts. nanoMAG magnesium sheet provides 200% higher strength and improved toughness over conventional magnesium, while also providing the strength of carbon steel sheet at one-fourth the weight.

Until now, magnesium alloy sheet has been cost prohibitive, difficult to form, and limited in availability. nanoMAG’s new material is targeted at lightweight applications in military vehicle armor, resorbable biomedical implants, and structural aerospace applications. The patent-pending process features isotropic fine-grained strengthening which permits low-volume manufacturing for specialty applications at a competitive cost.

“This is a significant advancement in magnesium that brings unprecedented performance in terms of strength and light weight, meeting the challenging demands of the automotive, military, biomedical, and aerospace markets,” explained Stephen LeBeau, president of nanoMAG. The company received a two-year $730,000 contract from the U.S. Department of Defense to develop lightweight composite military vehicle armor using nanoMAG sheet as the base structural carrier for the vehicle platform.

The Thixomolding Thermal Mechanical Process (TTMP), developed in conjunction with the University of Michigan, produces ultra-fine-grain “nanocrystalline” magnesium sheet with properties superior to conventional materials like steel, aluminum, and titanium. The nano structure is produced in-situ in a bulk form, avoiding the manufacturing issues associated with the handling of fine powders. The process uses Thixomolding technology to produce a sheet bar which is put through secondary thermo-mechanical heat processing. A key factor is the precise control of the microstructure which increases the yield strength of the original Thixomolded stock by more than 200% to more than 250 MPa along with 10% elongation. The result is an advanced magnesium sheet/plate with a superior strength-to-weight ratio than competitive materials.

nanoMAG’s mini-mill operation consists of discrete manufacturing cells capable of producing 500 tons per year with a modest initial capital investment. This unique manufacturing strategy reduces operating cost over traditional casting/rolling methods, permits economical short-run specialty products for niche markets, and allows incremental capacity to be brought online in response to market needs. The fine-grain sheet material also boasts greater formability, allowing fabrication of net-shape finished components currently not available.

nanoMAG estimates that the global market for magnesium sheet is 1250 tons a year, with revenues totaling $50 million. The global market for medical implants is estimated to exceed $4 billion with roughly 50% tied to ligament repairs that could benefit from improved fastening systems using magnesium resorbable implants. For demanding structural applications, laminated composites of magnesium sheet with carbon fiber have been successfully fabricated, offering a new class of materials with even greater strength and stiffness. Other promising applications including ultralight aerospace and fuel cell systems have also been identified.

nanoMAG and the University of Michigan received a National Science Foundation (NSF) grant to demonstrate the commercial feasibility of the material. Another NSF grant for $500,000 has been awarded for scale-up work. nanoMAG has a pilot/pre-production plant in operation in Ann Arbor, Mich. The company is actively seeking development partners to test and validate early pre-production samples tailored to end-use markets.