When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at Massachusetts Institute of Technology (MIT) have found that, in some situations, melting can actually inhibit metal bonding rather than promote it.
This surprising and counterintuitive finding could have serious implications for the design of certain coating processes or for 3D printing, which both require getting materials to stick together and stay that way. The research, carried out by postdocs Mostafa Hassani-Gangaraj and David Veysset and professors Keith Nelson and Christopher Schuh, is reported in two papers in Physical Review Letters and Scripta Materialia.
Schuh, who is professor of metallurgy and head of the Department of Materials Science and Engineering, explains that one of the papers outlines “a revolutionary advance in the technology” for observing extremely high-speed interactions, while the other makes use of that high-speed imaging to reveal that melting induced by impacting metal particles can impede bonding.