Abstract
The problems of the consequence of heat treatment of alloys performed using the concept of an ordering–separation phase transition are considered. Fe50Cr50 and Ni88Al12 alloys and U13 steel are used as examples to show that this transition occurs at a temperature specific for each system, and a change in the sign of the chemical interaction between alloy component atoms changes the direction of diffusion fluxes in alloys into the opposite direction, which changes the type of microstructure. The detection of this phase transition radically changes the generally accepted concepts of heat treatment of alloys. This finding calls for transmission electron microscopy investigations to modify the phase diagrams where this phase transition was detected. It is concluded that quenching of alloys from a so-called solid-solution field, which is usually performed before tempering (aging), is an unnecessary and useless operation, since the final structure of an alloy forms upon tempering (aging) irrespective of the structure existing before this heat treatment.
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Original Russian Text © Yu.I. Ustinovshchikov, 2015, published in Metally, 2015, No. 5, pp. 81–90.
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Ustinovshchikov, Y.I. Phase transition ordering–separation: A new approach to heat treatment of alloys. Russ. Metall. 2015, 745–752 (2015). https://doi.org/10.1134/S003602951509013X
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DOI: https://doi.org/10.1134/S003602951509013X