In this Phase I SBIR, Terves will develop processing routes to produce high thermal conductivity magnesium composites for use in heat transfer applications such as radiator materials. Terves will use and refine ultrasonic casting processes developed over the past three years and move into a magnesium based material using high aspect ratio carbon fibers and diamond particles by dispersing in a liquid state. The cast material will be rolled into sheet and tested for thermal and structural properties and compared to currently available materials. A successful program will result in a new, high thermal conductivity material that is lighter than current aluminum composites with the same or similar strengths. This composite will be applied in spacecraft for fast and effective heat transfer, enabling lighter thermal transfer systems by removing previous design constraints.