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S. Primig, G. Stechauner, E. Kozeschnik:
"Early stages of Cu precipitation in 15-5 PH maraging steel revisited - Experiments and Modelling";
Talk: PTM 2015 Solid-Solid Phase Transformation in Inorganic Materials, Whistler; 2015-06-28 - 2015-07-03.

Even though Cu precipitation during isothermal aging of Cu alloyed maraging steels has been studied thoroughly, no detailed investigations of the early stages of Cu clustering have been carried out so far. During continuous aging with a heating rate around 15 K/min of 15-5 PH maraging steel in a differential scanning calorimeter, two exothermal reactions are observed, one around 300°C and the other one around 500°C. These signals are attributed to the nucleation and growth of Fe-rich Cu clusters in the lower temperature range, followed by Cu-enrichment of these clusters and seamless transformation into bcc-Cu precipitates at higher temperatures. This investigation focuses on the characterization and modelling of the mechanisms governing these reactions. We first present a comprehensive experimental analysis based on dilatometry, differential scanning calorimetry, hardness testing, and atom probe tomography. The interpretation of the reactions is supported by thermo-kinetic simulations which substantially aid in understanding the underlying mechanisms.