by ErinRose Handy
"Is it scandium?"
This is the question du jour among mountain bike enthusiasts, and they're
willing to pay top dollarupwards of $2,500for a frame constructed
with it. Welcome to the world of high-performance sporting equipment,
where participants pay a premium for gear. Strength of material can save
athletes from devastating injury, and a single ounce can mean a competitive
An expert in designing
metals for mechanical performance, Assistant Professor Chad Sinclair studies
nanostructured metals. Unlike traditional engineering materials, the internal
structure of nanostructured metals is composed of sheets, ribbons or spheres
separated by as little as a few atoms. For instance, aluminum-scandium
alloys used in high-performance mountain-bike frames contain scandium
in the form of perfect spheres no more than five atoms in diameter, dispersed
within the aluminum. It is these very small spheres that impart the strength
to the lightweight aluminum bike frames.
a common adage in the industry-small is beautiful," says
Sinclair, referring to the creation of bulk materials from the
smallest of particles. Nanostructured materials can reflect properties
that do not obey simple laws deduced for bulk materials but instead
may offer extraordinary strength, hardness and resistance to fracture.
In many cases these mechanical properties can be obtained in combination
with other important properties, such as electrical and thermal
conductivity, temperature resistance, low density and/or magnetic
properties that make these materials relevant today and very promising
for future applications.
conducting pioneering research to develop materials on a microstructural
scale. Microstructure refers to the lengthscales within a material
that dictate its behaviour-such as how strong or hard it is. A
piece of metal may appear uniform, but it is in fact constructed
of constituent crystals, in turn made up of sub-crystals that
are in turn made from groupings of atoms. Each of these layers
in the material is associated with a smaller and smaller length.
The atom is the smallest length Sinclair works with.
with these scales, we can force materials to behave in a way that Mother
Nature never intended," says Sinclair. "We frustrate the material
by inserting roadblocks in the form of
internal boundaries." Imagine, for instance, a crack in a material.
For the material to break, the
crack must travel through the material. At each internal boundary, the
crack is forced to change direction or to slow down, thereby frustrating
the process of fracture. The more internal boundaries, the greater the
force that must be applied to keep the crack moving through the material.
Using a concept similar to genetic engineering, Sinclair can select a
desirable quality and replicate it from the most basic level, tailoring
engineering materials from the atomic scale up.
his position commenced in the Department of Materials Engineering
in 2001, Sinclair has worked on a variety of nanostructured materials,
including aluminum-scandium alloys used in sporting-equipment and
in aerospace industries, novel high-strength stainless steels used
in the automotive industry and copperniobium materials used in the
construction of very strong magnets used in magnetic-resonance imaging
(MRI) machines. The goal of his work has been to understand how and
why these materials perform in the way that they do and to find new
ways of fabricating advanced materials.
In the twenty-first
century, demand for new materials is being driven by the need for increasingly
sophisticated combinations of properties-mechanical, electrical and optical-
unavailable in traditional engineering materials. Nanostructured metals
appear well positioned
to address the desideratum. As long as there is a desire for lighter,
stronger, better, there will be an
increasing impetus to make materials engineered from the atomic scale.
This article was
first published in Ingenuity,
the Faculty of Applied Science Engineering newsletter.