The Ductile-brittle Transition in Metals
Many materials are malleable and ductile at higher temperatures, but become brittle when they are cooled to low temperatures. Most, but not all, FCC metals remain ductile even at temperatures approaching absolute zero. Most, but not all, BCC metals exhibit a ductile to brittle transition (DBT), which is often very abrupt, occurring over less than 10ºC. There is no phase change in the metal, only a dramatic change in its response to an applied stress. Ever since the liberty ships disasters of WW2 there has been intense research on the DBT in metals. Current understanding originates from research carried out by the great Soviet scientist Abram Joffé’s work in 1924 on common salt (NaCl). I will describe experimental research that shows the current thinking about the DBT in metals cannot be correct. Some of that research has existed for more than 50 years, but has been overlooked or ignored. Very recent experiments by Stan Lynch at Melbourne have revealed aspects of brittle fracture that are completely inconsistent with current thinking. Using these recent experimental discoveries I will describe a model for what I think may be going on in the DBT.
Emeritus Professor
Professor Adrian Sutton FRS a materials physicist specializing in the application of fundamental physics to understand and predict the structure and properties of technologically significant materials. His research spans classical and quantum mechanics, thermodynamics, statistical mechanics, and electronic structure, with a focus on problems that bridge theory, computation, and experimental relevance. Elected a Fellow of the Royal Society in 2003, he co-founded the Thomas Young Centre in 2005 and was the founding director of the Centre for Doctoral Training in Theory and Simulation of Materials in 2009.
