Concrete may have found it's killer app in graphene, but other metal alloys and carbon reinforced composites (ceramics and carbon) are hot with the nano-fabrication revolution. If you want to know where you can find an innovative, disruptive nanotech product, look at the metals market. From alloys and compounds to carbon reinforced composites, and a whole lot more, metal is one of the most fertile ground for the next generation of nano technology innovation. For most metals, the basic properties of strength and hardness, corrosion resistance and conductivity are the same regardless of grain size, meaning that the same equipment and manufacturing methods are used regardless of scale. But metal alloys are different and may include different kinds of particles or different kinds of chemical interactions to modify their properties. The most important properties of metal are its strength and ductility, with strength typically measured in Newtons (N) per square millimeter of cross-sectional area and ductility in meters per percentage. For comparison, wood has a strength of about 0.3 N/mm2 and a ductility of about 0.0002 m/% (with wood typically only ductile at strains below 20% and brittle at higher strains). Nano-sized metal particles and alloys are known as metal nanocomposites, and they have already found a variety of commercial applications in biodegradable metal implants that dissolve once the implant is installed. However, metal nanocomposites have been around in one form or another since the early 1990s, but the applications have been fairly limited. The two most promising areas of development are in the automobile and aerospace sectors, where materials may be required to meet stringent and sometimes inconsistent strength and ductility targets. Although there are a number of metallic nanocomposite materials available today, one area that has seen a lot of attention is the development of metallic glass alloys. At room temperature, glass is a brittle solid with an amorphous structure that can be melted and shaped into almost any shape. The amorphous structure is the key to glass’s strength and hardness, and it allows glass to easily combine with other materials to make stronger, harder and tougher composites. The metallic glass alloys are essentially glass, but with a fraction of the size of the typical glass particles. These metallic glasses are the strongest of all known materials, and may hold the potential to create some of the strongest metal structures ever manufactured. For example, one composite being actively researched is a new magnesium alloy with a glassy matrix that is 3-10 times more durable than the magnesium alloy it is mixed with. A company that is promoting this composite is the American company Magnesium Technologies. In 2008, Magnesium Technologies successfully created metallic glass alloys through a process called rapid-quenching. Magnesium metallic glass alloys also have the ability to be formed at much lower temperatures than typical conventional materials. However, at present, the cost of creating such composites is high, with some experts estimating that the cost per kg of material can be $10,000 to $15,000 per kg (in comparison, cast iron costs about $60 per kg, and titanium is about $1,000 per kg). Another area of development of metallic glass has been metal matrix composites. Although some of the earliest metal matrix composites, such as graphite-reinforced metal matrix composites, were highly effective in absorbing energy and converting it to heat, the development of non-carbon materials for this application has been sparse. Carbon is the most energy-dense material known, and this makes it useful as an energy storage medium for rechargeable batteries, which are critical components of the electrical grid. Metal matrix composites are an area of particular interest for this application, because metal matrix composites may have the ability to combine the best of several materials in one compound. They are extremely tough and stiff, and they can absorb energy better than graphite and can be more conductive than silicon. Metal matrix composites also offer corrosion resistance, can be made stronger and lighter than steel, and offer improved electrical and thermal conductivity. Their stiffness and strength may allow them to be used in energy storage applications as well as structural materials. Currently, the main material being used is carbon fiber reinforced plastic, which has proven to be a powerful material. Carbon fiber reinforced plastic also is being developed as a means of absorbing and storing energy. There are already strong carbon fiber reinforced composites being used in the automotive sector. Some of the carbon fiber reinforced plastics in the market today include carbon fiber reinforced plastic from companies such as Carbon Composites, Inc. (which provides composite structures for the aerospace and defense sectors), and Fibertek, Inc., which produces composite products for the healthcare, transportation and manufacturing sectors. There are several companies that are developing metal alloys and metal nanocomposites for commercial applications. One area that has seen a lot of development is in the automotive sector, and one of the most effective types of composite for this application is a fiber reinforced composite. In addition to the cost associated with creating composites such as metallic glass and carbon fiber reinforced composites, the main barrier to their commercialization has been the high cost of using these materials. However, recent developments in both processes and materials is making it cheaper and easier to manufacture. The automotive sector has been the primary driver in this area, but development is being expanded to many other areas. For example, the aeronautical industry has been leading the development of new composites materials such as metal matrix composites and carbon nanocomposites. The largest application of carbon nanocomposite materials in aerospace is in the structural panels for the aircraft. Metal matrix composite materials are also being used for aircraft components. The metal nanocomposites revolution While the metals industry is the main driver for metals in the nanotechnology market, it may not be the strongest competitor. The metals industry is mostly about cost; it is about how much metal you can get out of the raw materials and how much you need to pay the smelters, refiners and fabricators. It is about optimizing how much energy and energy efficiency is needed to produce those metals. The metals industry’s main complaint against metals nanocomposites is that the process is too complex. It is too expensive. And it is not as predictable as using metals. However, a number of the metals companies believe that the current process used to create metallic nanocomposites is so complex that it is actually preventing the industry from using more advanced materials. The biggest challenge facing metal nanocomposites is that there is no efficient means for developing the materials in an R&D lab, fabricating them using a metal fabrication machine, and then testing in an industrial environment. The process of introducing metallic glass or metallic matrix composites to a commercial application has proven to be very costly and time-consuming. For this reason, the aerospace industry has been the biggest driver for the metals industry with regard to using metallic nanocomposites. For example, the aerospace industry has been driving the metallic glass and metallic matrix composites market, which have seen some of the best returns. So, what does the future hold? Like any field that is growing, the metals industry is struggling to understand the technology as it moves forward. This has prevented the industry from catching up to the speed with which products are changing. On the positive side, the metals industry is not only watching the development of the metal nanocomposites, it is actually a leader in some of these areas, such as metals for sustainable development and alternative energy storage and production. With the development of next-generation batteries, power plants, light-emitting diodes and much more, there is a growing interest in incorporating metallic nanocomposites and nano-reinforcement to replace the high cost of materials in current metal products. One example is the recent success of the magnesium alloy research and development, where the metal alloy companies are finding themselves in the middle of this market-leading trend. One potential area of disruption for the metals industry in the coming years is what I call the “metals-on-chip” trend. With the development of microprocessors and the explosion of software, a number of the current markets for metals technology will become much more relevant, such as sensors, wearable technology and energy storage. Another trend that could potentially disrupt the metals industry is the development of microelectromechanical devices (MEMs), which are miniature sensors that incorporate the electrical and mechanical functions. These are potentially a high-volume market. But, the metal nanocomposite technology is not yet at that point, with its low penetration, high cost and complexity. While the current metals industry is more focused on the materials and the costs associated with them, the next generation will be a much different story. With the nanotechnology revolution, the cost of these materials will become a huge driving force in the next-generation metals industry. The nanotechnology revolution will help metals companies catch up with some of the high-value, high-cost metal applications, and in some cases, surpass them. As a result, the next-generation metals industry will be an interesting transition between the metals industry we currently know and the metals industry of the future. Kathleen J. DeMeester is a Materials Science and Engineering professor at the University of Illinois and the founder of nanosurfaces.com, a site that focuses on how nanotechnology will transform the future of everyday objects. She also is the founding editor of the journal Materials Horizons and is a member of the National Academy of Engineering. The views expressed are those of the author and are not necessarily those of Scientific American. ABOUT THE AUTHOR