'Metallic wood' is as strong as titanium, but much lighter

A group of researchers from Penn University, the University of Illinois at Urbana–Champaign, and the University of Cambridge have made a breakthrough with a new material that is very strong, yet very light. The material is a sheet of nickel with nanoscale pores that make it as strong as titanium, but four to five times lighter. The material has nanoscale pores on its surface that are made using a self-assembly process making the porous metal similar to natural materials like wood.

The empty space in the creation could be infused with other materials. The team says that if the pores were infused with anode and cathode materials, the metallic wood would be able to be used for things like an airplane wing or a prosthetic leg that is also a battery. The material is referred to as metallic wood because of its density, which is about that of wood, but also due to the cellular nature of the material.

Cellular materials are porous, which is what we see when we look at wood. The team says that some parts of natural wood are meant to provide support to the material and other, more porous sections are meant to transport to and from cells inside the tree. The structure of this new material is similar.

Areas of the material are thick and dense with strong metal struts while others are porous with air gaps. The struts in the material are about 10 nanometers wide. The material is created starting with tiny plastic spheres that are a few nanometers in diameter that are suspended in water.

As the water evaporated the spheres settle and stack like cannonballs giving an orderly, crystalline framework. Those spheres are then infused with nickel using electroplating. Once the nickel is applied, the spheres are dissolved with a solvent leaving an open network of metallic struts in the material. About 70% of the space in the material produced is empty space giving it a density on par with water and allowing the material to float.