首页|Verification of the ability of Cu to dissolve in BCC δ in a δ-γ Solid Solution above 1200 °C and boosting δ nano-hardness in Cu-containing PHSS
Verification of the ability of Cu to dissolve in BCC δ in a δ-γ Solid Solution above 1200 °C and boosting δ nano-hardness in Cu-containing PHSS
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NSTL
Elsevier
? 2022 Acta Materialia Inc.Because Cu is an austenite γ stabilizer, it is thought that Cu only dissolves in the FCC γ phase but not in the BCC δ when Cu-containing PHSS are treated in a dual δ-γ solid solution at high temperature. However, the nano precipitation of Cu in the allotriomorphic δ found upon quenching from 1295°C. To study this unexpected phenomenon, thermodynamic calculations were performed. The predicted solubilities of Cu in the γ and δ at 1295°C were 3.52 and 1.99 wt%. Consequently, quenching the solid solution from 1295 to 25°C results in the ultra-supersaturation of Cu in the δ. The vacancy concentration in the δ solution was estimated to change from 1024 vac./m3 at 1295°C to105 vac./m3 at 25°C; quenching yields excess vacancies. Thus, Cu-rich nanoparticles precipitate in the δ matrix through the interdiffusion of the ultra-supersaturated Cu and excess vacancies.
Dual phasesNanoindentationPrecipitationStainless steelsTransmission electron microscopy (TEM)
NSTL
Elsevier
