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This article lacks information on the subject matter's importance. If you are familiar with it, please expand the article, or discuss its significance on the talk page. The introduction of this article does not provide enough context for readers unfamiliar with the subject. Please fix the introduction or article as you see fit. HALL PETCH, added by David Woroner. The Work is owned by the people mentioned herewitin.
Microstructure and Hall-Petch behavior of Fe-Co-based Hiperco© alloys
Chang-He Shang, R.C. Cammarata, and T.P. Weihs
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218
C.L. Chien
Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218
The microstructure and hardness of Fe-Co-based Hiperco© alloys were investigated. Scanning electron microscopy revealed elongated grains in the as-received (cast and cold-rolled) alloys, and samples containing Nb had second phase precipitates. Annealing of alloys for 1 to 3 h at temperatures in the range 700 to 800 °C resulted in grains becoming equiaxed. In the Nb-containing alloys, the original precipitates dissolved and new precipitates appeared. The rate of grain growth decreased with increasing Nb content, suggesting that Nb or Nb-containing precipitates were responsible for a reduction in the grain boundary mobility. The hardness as a function of grain size in the annealed samples of all of the alloys could be plotted on the same Hall-Petch curve, indicating that the yield strength of these alloys is governed by the grain size, independent of the alloy composition and volume fraction of precipitates.
HALL & PETCH, Two different scientists did studies in the 1950's that basically discussed the slippage attributed to the inability of structures to maintain their hardness. Their are other papers directly relating to the initial work/discovery of these two men at: http://dcwww.camp.dtu.dk/~schiotz/papers/risoesymp/html/node3.html
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