Former engineering dean honored for research contributions

Harold Brody, Distinguished Professor of Materials Science & Engineering, was recently honored by the Minerals, Metals & Materials Society for outstanding contributions in the field of solidification science.

He received the 2009 Bruce Chalmers Award during the society’s annual meeting in San Francisco in February.

Research on alloys
Solidification science is the study of the processes by which materials change from a liquid to a solid state. Many everyday objects – from high-end cookware to bicycle frames – as well as sculpture, turbine blades, and automotive components, are produced using a solidification process in the manufacturing sequence.

Brody’s research has focused on the solidification of alloys. To make an alloy, metallurgists may heat two or more elements to a liquid phase, mix them together at a proportion that provides a uniform solution, and transfer the molten alloy to a mold, where it solidifies in a manner that produces desired properties in the cast product.

“Think of tea,” says Brody.

“Hot tea accepts more sugar than iced tea, with the sugar remaining bound in solution, to a critical tipping point: the solubility limit. When sweetened hot tea is cooled, sugar crystals can begin to form as precipitates. The solid crystals are richer in sugar than the sweetened liquid tea. When we blend metals in an alloy, the alloying elements, in general, are more soluble in the liquid than the solid phase.”

Brody notes that “solidification takes place over a range of temperatures, and the composition of the solid differs from the composition of the liquid from which it forms.

Branched structures
Typically, to efficiently redistribute alloying elements between the liquid and solid phases, the solidifying crystalline solid develops tree-like, highly branched structures called dendrites.

” The distinctive “jack frost” that forms on windows in winter is a familiar example of dendritic crystal formation.

Brody says the Chalmers Award is a very personal honor.

Chalmers (1907-1990), a renowned professor of applied physics at Harvard University, is regarded as the father of solidification science. As a graduate student at MIT, Brody belonged to a research group overseen by Professor Merton Flemings, who collaborated with Chalmers.