PhD student’s aluminum alloy tests good for science & the environment
By Amie Lynn Shirkie
Passionate about contributing to knowledge and research in the material sciences, U of S student George Quainoo hopes his doctoral work on aluminum alloys will have important consequences for the automotive industry and the environment.
Having received his degree in Physics at the University of Cape Coast in Ghana, Quainoo applied his experience in “the building blocks of science and engineering” to Mechanical Engineering. He began his PhD under the supervision of Professor Spiro Yannacopoulos in 1999.
Quainoo says he began his research “with the goal of contributing to the improvement of the environmental and economical impact of the automobile on society.” The background for his study stems from the automotive industry’s recent concern to meet Corporate Average Fuel Efficiency standards, which seek to reduce vehicular weight, thereby increasing fuel efficiency and cutting back on harmful emissions into the atmosphere.
One efficient way of achieving this has been to use lighter materials such as aluminum alloys. AA6111, which is manufactured by the Alcan Aluminum Company in Kingston, Ont., is a popular aluminum alloy used for automobile body panels. According to Quainoo, AA6111 is the material of choice for North American automobile manufacturing companies, “due to its unique combination of formability, paint-bake strengthening and superior corrosion resistance.”
Quainoo’s research focuses on evaluating the effects of “cold work” on precipitation in AA6111. Major automotive companies such as Ford, GM and Audi already use AA6111 aluminum alloys. Quainoo hopes that by assessing ways of working with the alloy to make it stronger, his study will encourage more companies to use it.
Cold work, according to Quainoo, is a process in which an alloy is formed at room temperature into its desired shape. This leads to the formation of “high energy sites” or weak spots in the material. This is followed by a process of “precipitation”, in which the aluminum alloy is placed at an intermediate temperature over a period of time in order to increase its strength, especially at these weak points.
In order to determine the effect of cold work on precipitation, Quainoo preformed a number of investigative experiments, such as tensile testing, microhardness measurement, differential scanning calorimetry, scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy, “in addition to other metallographic and data analysis techniques.” All these tests enabled him to characterize the properties of the AA6111 alloy under a variety of conditions.
Quainoo says, “The results show a considerable improvement in yield and tensile strength with increasing levels of cold work.”
He further analysed the kinetic parameters for various solid-state reactions in the alloy, and was able to determine that cold work significantly affected the precipitation kinetics of AA6111. According to Quainoo, these results “compare reasonably well with the literature for similar alloys.”
Quainoo believes the use of AA6111 in automobiles will have an important impact on the environment: “Because of its light weight, it encourages fuel efficiency, which results in fewer emissions into the atmosphere.” So far, AA6111 is only used on auto body panels, but Quainoo foresees a future in which an all-aluminum vehicle might exist, as other alloys are currently being developed for application in other parts of the automobile.
Quainoo says his results have been well received in the material science community, leading to a number of publications, conference papers, presentations at national and international scientific meetings, as well as “a positive contribution to knowledge.”
He hopes to continue his research, pursuing his “passion” to contribute to knowledge in material science.
Amie Lynn Shirkie writes graduate student profiles for the College of Graduate Studies & Research.