STTR Phase II : New Process for High Strength/Weight Net-Shape Auto and Aero components from Mg Sheet

This Small Business Technology Transfer (STTR ) Phase II project aims to scale-up and commercialize a low cost and simple process to produce high strength/density Magnesium (Mg) alloy sheet; using Thixomolding Thermomechanical Processing (TTMP). TTMP avoids the decades-long barriers of twinning and shear band deformation that limits the formability of commercial coarse-grained Mg alloys, rather, in TTMP fine isotropic grains are molded in the first Thixomolding step and then these are thermomechanically processed to impose continuous dynamic recrystalization to finer grains of 0.8 to 2 microns. In this fine grained mode of processing, twinning and shear banding are minimized while slip and grain boundary sliding are promoted. The common intermetallic phases of Mg alloys are also refined to nanometer size so that they can serve as dispersion hardeners. The end result of the refined microstructures is an increase of both strength and ductility. The mechanism may apply also to Titanium (Ti) and Beryllium (Be) alloys. The broader/commercial impacts of this project are fuel and pollution savings in automobiles and trucks; fuel and payload benefits in aerospace; energy savings in batteries and fuel cells; and medical benefits in bio-replaceable body implants. Commercially, this project will result in a new U.S. business in manufacture of superior low cost Mg sheet.