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 (beta(1) + beta(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 beta(3) (Cu2AlMn) + beta(1) (Cu3Al) -> beta(3) (Cu2AlMn) reaction is strongly dependent on the heating and cooling rates. The Sn addition to the Cu-11%Al-10%Mn alloy stabilizes the ferromagnetic beta(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 beta(3) phase. Nonetheless, the formation of Cu5Gd 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.