Lyle D. Zardiackas, Ph.D., FADM
Professor Zardiackas primary research interests are in three
areas. These areas include stress
corrosion cracking (SCC),
corrosion
fatigue, and 
failure
analysis of metals and retrieved metallic implants.
Because of these interests, he has received numerous industrial
research grants and contracts from both primary metals suppliers
and manufacturers of implantable devices. He and his group
have presented many papers at national and international meetings
and published extensively on these subjects. Most of his work
over the past 5-10 years has been in the area of slow strain
rate stress corrosion cracking and corrosion fatigue of metals
used in the biomedical industry such as titanium and stainless
steel alloys.
The focus of this work has been to characterize and compare
these properties both in and out of a simulated physiological
environment for metallic alloys with a long history of implant
applications as well as working with industrial partners during
the development of new metal alloys and processing methodologies.
Once these properties have been characterized, the scope of
this research has been extended
to observations and determinations of different mechanisms
of fracture
as a function of the applied mechanical stress spectrum. This
work has contributed to the introduction of several new alloys
to the biomedical and other markets.
It is largely due to the focus of this research that the resources
for the evaluation of mechanical properties, compositional
and
phase analysis and metallography have been developed to such
a substantial extent. A number of funded research grants are
currently in place to expand these areas of research. These
areas of research are dedicated to a more thorough understanding
of the metallurgical, physical, and electrochemical conditions
which affect the mechanisms of degradation or failure of materials
from which metallic implants are produced. Further to this
goal comes the development of new metals, and alloys with
improved
properties as relates to their use for implantable devices.
The third area of primary interest relates to the other two
areas. Evaluation of the results of mechanical fracture
and
its relation to the environment in laboratory experiments is
used to an understanding of the reasons for failure of an
implantable
device. Much of this understanding is gleaned from the examination
of the changes in morphology of surfaces near the fracture
surface
which led to fracture initiation and determination of the mechanisms
of crack propagation by examination of the fracture surface
itself. Failure analysis of device retrievals is used as a
guide to the understanding of in vivo failure mechanisms
and the possible
areas for improvement of the materials and/or to enhance material
selection for the device designer.
