Thermodynamic measurements on Ag - 28% Cu nanopowders processed by mechanical alloying route

Graphical abstract: Crystallite size (XRD measurements) and enthalpy increment (H_T − H₂₉₈) (drop calorimetry data) of the nanozised Ag - 28% Cu powders as a function of temperature. - Highlights: • We report relevant data for thermodynamic stability of mechanical alloyed Ag - 28% Cu nanopowders. • Enthalpy increment and heat capacity data have been measured by drop calorimetry. • The effect of milling time on the particle size and energetic parameters is evidenced. • Correlation between thermodynamic and structural data of Ag - 28% Cu nanopowders is discussed. - Abstract: The paper is devoted to the investigation of the thermodynamic properties of Ag - 28% Cu powders processed by mechanical alloying route at two different milling times (20 and 80 h). Thermodynamic properties represented by the heat capacity (C_p) and the enthalpy increment (H_T − H₂₉₈) have been obtained in the temperature range from ambient to 1073 K by drop calorimetry using a multi-detector high temperature calorimeter SETARAM MHTC-96. A critical comparison of the isothermal enthalpy measurements with the dynamic differential scanning calorimetric (DSC) results has been made to reveal the occurrence of the micro-relaxation process, as well as of the correlative effects of decomposition and growth processes. New features related to the effect of the milling time and crystallite size on the thermal behavior and energetic parameters were evidenced. The correlation between thermal stability and microstructure of the sample obtained after 80 h processing has been investigated by the evaluation of the in situ controlled annealing powder X-ray diffraction patterns (XRD)