How about high temperature and transformation plasticity in metal? Dose the Hall-Petch model works for High temperature as room temperature? according to my experimental results at high temperature grain size increase but deformation decrease, i am confuse about this result, and i am working in mechanism of this result, does anyone know the mechanism?
Ductility is ability of material to plastically deform, this involves a role of dislocations.In elastic range only stretching of the bonds between the atoms plays a role while in plastic range dislocations already present or newly developed plays a role. how freely dislocations can move (breaking of the bonds between the atoms) defines the ductility of the material. Smaller the grain size the more is the grain boundary area unit volume where these dislocation are restricted and may pile up causing strengthening the material and hence reducing the ductility. on the other hand when the grain size is large the dislocation can more freely move hence causing higher ductility. Grain size at nano-level can have higher ductility due to grain boundary sliding. You can study this in any good metal strengthening text. and also the fractography of the ductile materials and its charters tics by microsopy
Is there any new discovery about grain size and ductility...
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