Charles J. McMahon, Jr.
Materials Science and Engineering (MSE)
Research Expertise: Mechanical Behavior | Metals | Surfaces & Interfaces
High-strength materials can undergo failure by decohesion, usually along grain boundaries, if a high tensile stress is applied while a surface-adsorbed low-melting-point element is present on the surface at a temperature where the surface element is mobile. A theory has been developed to model the diffusion-controlled crack-growth, and it is being tested with a variety of materials, both polycrystals and bicrystals, including alloy steels, copper-based and nickel-based alloys, and an iron-silicon alloy. The surface elements originate from either a vapor or a surface coating (solid or liquid) or from solid solution in the alloy being studied. This phenomenon is actually widespread in engineering materials, but the mechanism is not widely appreciated.
Sc. D. Physical Metallurgy 1963 - Massachusetts Institute of Technology; B.S. Metallurgical Engineering 1955 - University of Pennsylvania