The method for the deconvolution of overlapping DSC peaks here proposed has been used by the first time for the quantitative determination of the enthalpies associated to the phase transitions undergone during the aging of an alloy. They have been determined the enthalpies evolved along the first and the second overlapping DSC traces of Cu-10 wt%Ni-5.5 wt%Sn alloy, which are associated, respectively, to the spinodal decomposition of the alloy and the segregation of a DO (CuNi)Sn tetragonal phase. The fraction of the DO phase (responsible of the aging hardening of this alloy) has been successfully determined from DSC as a function of the annealing treatment, while TEM and XRD failed for this purpose. It has been demonstrated that a threshold higher than 50% of crystallization of the DO phase is required for achieving a significant increase of the hardness as a function of the crystallization percentage. These results suggest that microcalorimetric measurement can be a powerful tool to establish quantitative relationships between the mechanical, electrical or functional properties of alloys and their structural changes undergone by aging.

The authors would like to acknowledge the facilities provided by the Instituto de Ciencia de Materiales de Sevilla (Spain) and the Departamento de Ciencia de Materiales of the University of Chile (Chile). One of us (A. Perejón) also thank VPPI-US for the AP current contract. Financial support by projects CTQ2014-52763-C1–R (Ministerio de Economia y Competitividad, Spanish government-FEDER) and TEP-7858 (Junta de Andalucia-FEDER) is acknowledged.