text: Composite metal foam is made from a combination of homogeneous hollow metal spheres with a metallic matrix surrounding the spheres. This closed-cell metal foam isolates the pockets of air within and can be made out of nearly any metal, alloy, or combination. The sphere sizes can be varied and fine-tuned per application. The mixture of air-filled hollow metal spheres and a metallic matrix provides both light weight and strength. The spheres are randomly arranged inside the material but most often resembles a simple cubic or body-centered cubic structure. CMF is made out of about 70% air and thus, weighs 70% less than an equal volume of the solid parent material. Composite metal foam is the strongest metal foam available with a 5-6 times greater strength to density ratio and over 7 times greater energy absorption capability than previous metal foams. CMF was developed at North Carolina State University by the inventor Afsaneh Rabiei with four patents in her name, all entitled "Composite Metal Foam and Method of Preparation Thereof" (US Utility Patents 9208912, 8110143, 8105696, 7641984), and CMF is currently proprietary technology owned by the company Advanced Materials Manufacturing.