Unbreakable cell phone covers may soon be available in your neighbouring markets, thanks to researchers at Massachusetts Institute of Technology (MIT) who have made a significant progress in understanding why some specific metallic alloys can form glasses while others cannot.
Research leader Carl. V. Thompson, the Stavros Salapatas Professor of Materials Science and Engineering and director of the Materials Processing Center at MIT, says that the team's study describes a way to systematically find the promising mixes from among dozens of candidates.
Writing about their work in the journal Science, the researchers describe glasses as solids whose structure is essentially that of a liquid, with atoms arranged randomly instead of in the ordered patterns of a crystal.
Glasses are generally produced by quickly cooling a material from a molten state in a process called quenching, according to background information in the research article.
"It is very difficult to make glasses from metals compared to any other class of materials, such as semiconductors, ceramics and polymers," Thompson said.
The researcher said that scientists have for decades focused on "understanding and on exploiting the remarkable properties of these materials, and on understanding why some alloy compositions can be made into glasses and others cannot."
However, according to Thompson, none of the scientists have been able to solve those mysteries to date.
He said that the new study did "provide a very specific and quantitative new insight into the characteristics of liquid alloys that can most readily be quenched into the glassy state," and thus provided a much more rapid way of discovering new alloys with the right properties.
Thompson joined forces with MIT post-doc Johannes A. Kalb with Professor Yi Li and graduate student Qiang Guo at the National University of Singapore to produce an array of different alloys with slightly varying proportions of two metals, each deposited on a separate microscopic finger of metal.
The researchers analysed the changes in density of each different mixture when the glass crystallized, and found that there were a few specific proportions that had significantly higher density than the others.
According to them, those particular alloys were the ones that could readily form glasses.
The team said that two of the three of those special proportions were already known glass-forming alloys, but the third was a new discovery that could even lead to a solution to the longstanding puzzle of why only certain alloys make glasses.
"I expect these new results, and the technique we developed to obtain them, will play a key, and hopefully decisive, role in solving the mystery of metallic glass formation," said the researchers.
Thompson said that such materials could have a variety of applications because of their unusual physical and magnetic properties.
Given that such glasses are unusually hard mechanically and have a high degree of springiness, the researchers say that they can be useful for some sports equipment like golf clubs or tennis rackets.
Thompson said that metallic glasses, though relatively expensive, might not be considered costly by those people who are interested in the best-performing sports equipment, or in virtually unbreakable housings for cellphones.