The microstructural evolution of a 2101 lean duplex stainless steel (DSS) during isothermal aging from room temperature to 470 °C was investigated using thermoelectric power (TEP) measurements to follow the kinetics, atom probe tomography, and transmission electron microscopy. Despite the low Ni, Cr, and Mo contents, the lean DSS was sensitive to α–α′ phase separation and Ni–Mn–Si–Al–Cu clustering at intermediate temperatures. The time–temperature pairs characteristic of the early stages of ferrite decomposition were determined from the TEP kinetics. Considering their composition and locations, the clusters are most likely G phase precursors.
