DARPA's Materials with Controlled Microstructural Architecture (MCMA) program is seeking ways to control and engineer materials at a fundamental level. If possible, DARPA would like to control the microstructure of materials right down to the micron level.
Control at the microstructure level allows researchers to develop materials with greatly enhanced properties. For instance, as demonstrated in the video below, DARPA was able to construct a material so light that it can rest atop a bubble. MCMA researchers are working toward the goal of developing a material that is as strong as steel, but as light as a plastic. To do so, they are exploring the full range of properties that can be manifested as functions of truss design and weight in a material’s microstructure.
DARPA has also developed lightweight materials that can absorb energy without failing, or breaking. As shown in the following video — previously released in conjunction with a journal article on ultralight metallic microlattices — the nickel microtruss structure can achieve a 40% strain level without collapsing; in fact, it fully recovers its form. DARPA is exploring how much strength and energy absorption can be combined in the same material without damaging it.
The ultimate objective of the MCMA program is to be able to develop materials in the future with properties tailored to meet specific mission requirements.
Fans of Edgar Rice Burroughs recall harbenite, an amazing ultralight metal, from his 1929 book Tarzan at the Earth's Core:
...Erich von Harben is something of a scientist and explorer himself, and the last time that I saw him he had just returned from a second expedition into the Wiramwazi Mountains, where he told me that he had discovered a lake-dwelling tribe using canoes made of a metal that was apparently as light as cork and stronger than steel. He brought some samples of the metal back with him..."
"...It is not my intention to weary you with a recital of the details of the organization and equipment of the Pellucidarian expedition, although that portion of it which relates to the search for and discovery of the native mine containing the remarkable metal now known as Harbenite, filled as it was with adventure and excitement, is well worth a volume by itself."
Another way to look at it is that DARPA is trying to create science-fictional materials. DARPA program engineers are encouraged to check out these science fictional materials:
High tensile strength material; used in collapsible structures (from Frank Herbert's 1965 novel Dune).
A strong, transparent material (from the 1930 novel Brigands of the Moon by Ray Cummings.
Unusual alloy combines a metal and a gas (from Robert H. Wilson's 1931 story Out Around Rigel)
Steel that did not rust or corrode (from Hugo Gernsback's 1911 novel Ralph 124c 41 +).