Hall-Petch equation

== English == === Etymology === Independently discovered by English scientists Eric O. Hall and Norman J. Petch, in 1951 and 1953 respectively. === Proper noun === the Hall-Petch equation (materials science) A relationship between the yield point and grain size of a material given by the equation σy = σ0 + ky * d-0.5, where σy is the yield stress, d is the average grain diameter, and σ0 and ky are constants specific to a particular material.