Newly developed metallic "micro-lattice" material is world's lightest

Earlier this year we looked at a "multiwalled carbon nanotube (MCNT) aerogel" -also dubbed "frozen smoke" - that, with a density of 4 mg/cm3, became the world's lightest solid material. Now frozen smoke has been knocked off its perch by a new metallic material with a density of just 0.9 mg/cm3, making it around 100 times lighter than Styrofoam. Despite being 99.99 percent open volume, the new material boasts impressive strength and energy absorption, making it potentially useful for a range of applications.

The 0.01 percent of the material that isn't air consists of a micro-lattice of interconnected hollow nickel-phosphorous tubes with a wall thickness of 100 nanometers - or 1,000 times thinner than a human hair. These tubes are angled to connect at nodes to form repeating, three-dimensional asterisk-like cells.

The new material draws parallels with large structures, such as the Eiffel Tower, which is incredibly light and weight-efficient thanks to its hierarchical lattice design. As an illustration of just how efficient such a design is, if the 7,300 tonnes of metal used in the Eiffel Tower were melted down it would fill just six centimeters (2.4 in) of the structure's 125 m2 (1,345 square ft) base.

The ultralight micro-lattice material shows the same concept can also reap benefits on a much smaller scale. The wall thickness of the hollow tubes can be measured in nanometers, the diameter of each tube in microns, each tube length in millimeters, and the entire micro-lattice in centimeters - or even one day, meters, claim the researchers.

In addition to its ultra-low density, the researchers say the new material's micro-lattice architecture gives it extraordinarily high energy absorption with the ability to completely recover from compression exceeding 50 percent strain. This is due to the fact that the extremely small wall thickness-to-diameter ratio of the material makes the individual tubes flexible. Its impressive properties could see it used for battery electrodes, catalyst supports, and acoustic, vibration or shock energy damping.

The novel material was developed by a team of researchers from the University of California, Irvine (UC Irvine), the California Institute of Technology (Caltech) and California-based company, HRL Laboratories. for DARPA.

The research team's paper, "Ultralight Metallic Microlattices," appears in the November 18 issue of Science.