YSM Issue 86.4

A Shattering Discovery:
Optimizing Microstructures
TO ENHANCE DURAB ILITY
BY DEEKSHA DEEP
Picture your ideal mobile phone — it
probably has a sleek design with a
polished screen and a slim but fragile
body. Now imagine that phone falling: either
off the edge of your bed, out of the car as
you open the door, or even clumsily out of
your hand as you pull it out of your pocket.
The sound and sight of a shattered screen
that would likely follow are all too familiar,
but what if there were a way to alter the
properties of the materials used in our devices,
our buildings, and the very infrastructure on
which our lives are based? Yale researchers
Professor Jan Schroers and Dr. Baran Sarac
have tackled this question by developing a
process to enhance the physical properties of
a material utilizing “artificial microstructures.”
The Importance of Microstructures
Every material has measurable physical
properties, such as tensile strength, ductility,
and plasticity. These properties can be
improved if a compatible microstructure
is coupled with the desired material.
Microstructures, which can only be seen using
optical microscopes, can function to absorb
stress, thus increasing a material’s strength and
durability. The key features of microstructures
include shape, size, volume, distribution, and
spacing between each individual element. If a
microstructure can be altered in a controlled
manner to produce a structure analogous to
a particular material, the material’s quality and
www.yalescientific.org
durability can be greatly improved.
An example of the utility of microstructures
is their role in improving the quality
of refractory materials. Useful for the
construction of industrial equipment such
as kilns, incinerators, and reactors, refractory
materials can withstand heat while retaining
durability. Embedding microstructures in these
materials greatly enhances their refractory
properties. Furthermore, increasing the
efficiency of materials decreases consumption
and costs. For example, since 1970, the US has
decreased its consumption, and by extension
waste, of refractories by over 64 percent.
Applications of microstructure biomaterials
used in hip replacements are not refractory
materials, they match in elasticity with the
body and are biocompatible. For example,
biomaterials (ex. hip replacements) to be
used in vivo need to match in elasticity with
the body parts they replace. The desired
mechanical properties can be achieved via
directed construction of microstructures.
With such drastic improvements in sight, there
is clearly incentive to further study and apply
microstructures to more materials.
Introduction to the Project
Professor Schroers and his team used a
class of material called Bulk Metallic Glasses
(BMGs) for their study on microstructures.
These materials mimic many properties
of metals but are far more resilient and
IMAGE COURTESY OF BARAN SARAC
Dr. Baran Sarac (left) and Professor Jan
Schroers (right) are the co-authors and
main researchers in determining the
optimal microstructure for BMGs.
surprisingly plastic, or moldable. This unique
conglomeration of properties makes BMGs
promising in many areas of application
from large structures down to nano-scale
projects. Unfortunately, there is a barrier to
the implementation of BMGs in improved
materials: They have a gaping lack of
tensile ductility, which prevent them from
being worked into a desired shape without
significant stress. This issue with what would
otherwise be a perfect candidate for the
future reshaping of materials was the focus
for the “artificial microstructure” approach
implemented by Schroers and his team.
November 2013 | Yale Scientific Magazine 25