Effects of Sn and Gd on the (β1 + β3) stability field in the Cu-11%Al-10%Mn alloy

Effects of Sn and Gd additions on the (β 1 + β 3 ) field in the Cu-11%Al-10%Mn alloy were studied by in situ X-ray diffraction, differential scanning calorimetry, non-isothermal kinetics, and magnetization measurements as a function of the temperature. The microstructures were investigated using optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The results showed that the β 3 Cu 2 AlMn + β 1 Cu 3 Al → β 3 Cu 2 AlMn reaction is strongly dependent on the heating and cooling rates. The Sn addition to the Cu-11%Al-10%Mn alloy stabilizes the ferromagnetic β 3 phase. In the Sn-containing alloy, the miscibility gap transition is followed by the martensitic transformation at about 560 K. Both Sn and Gd additions have extended the stability field of the ferromagnetic β 3 phase. Nonetheless, the formation of Cu 5 Gd precipitates slows the miscibility gap transition on heating, which may be associated with the reduction of the ferromagnetic phase amount at room temperature in the Cu11%Al10%Mn3%Gd alloy.