Frank–Read source

In materials science, a Frank–Read source is a mechanism explaining the generation of multiple dislocations in specific well-spaced slip planes in crystals when they are deformed. When a crystal is deformed, in order for slip to occur, dislocations must be generated in the material. This implies that, during deformation, dislocations must be primarily generated in these planes. Cold working of metal increases the number of dislocations by the Frank–Read mechanism. Higher dislocation density increases yield strength and causes work hardening of metals.

It was proposed by and named after British physicist Charles Frank and Thornton Read.

Charles Frank detailed the history of the discovery from his perspective in Proceedings of the Royal Society in 1980. In 1950 Charles Frank, who was then a research fellow in the physics department at the University of Bristol, visited the United States to participate in a conference on crystal plasticity in Pittsburgh. Frank arrived in the United States well in advance of the conference to spend time at a naval laboratory and to give a lecture at Cornell University. When, during his travels in Pennsylvania, Frank visited Pittsburgh, he received a letter from fellow scientist Jock Eshelby suggesting that he read a recent paper by Gunther Leibfried. Frank was supposed to board a train to Cornell to give his lecture at Cornell, but before departing for Cornell he went to the library at Carnegie Institute of Technology to obtain a copy of the paper. The library did not yet have the journal with Leibfried's paper, but the staff at the library believed that the journal could be in the recently arrived package from Germany. Frank decided to wait for the library to open the package, which did indeed contain the journal. Upon reading the paper he took a train to Cornell, where he was told to pass the time until 5:00, as the faculty was in meeting. Frank decided to take a walk between 3:00 and 5:00. During those two hours, while considering the Leibfried paper, he formulated the theory for what was later named the Frank–Read source. A couple of days later, he traveled to the conference on crystal plasticity in Pittsburgh where he ran into Thorton Read in the hotel lobby. Upon encountering each other, the two scientists immediately discovered that they had come up with the same idea for dislocation generation almost simultaneously (Frank during his walk at Cornell, and Thornton Read during tea the previous Wednesday) and decided to write a joint paper on the topic. The mechanism for dislocation generation described in that paper is now known as the Frank–Read source.

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