Effect of Ag addition on phase transitions of the Cu–22.26 at.%Al–9.93 at.%Mn alloy

The phase transitions that occur in the Cu–22.26 at.%Al–9.93 at.%Mn and Cu–22.49 at.%Al–10.01 at.%Mn–1.53 at.%Ag alloys after slow cooling were studied using differential scanning calorimetry at different heating rates, microhardness changes with temperature, magnetization changes with temperature, scanning electron microscopy and energy dispersion X-ray spectroscopy. The results indicated that the presence of Ag does not modify the transition sequence of Cu–Al–Mn alloy, introduces a new transition due to the (Ag-Cu)-rich precipitates dissolution at about 800 K, and changes the mechanism of DO3 phase dissolution. This mechanistic change was analyzed and a sequence of phase transitions was proposed for the reaction.

► A kinetic mechanism for the dissolution of DO3 phase is suggested.
► The intermediate phase interferes on the kinetics of the DO3 phase dissolution.
► The presence of Ag changes the stability of intermediate phase.