Effect of homogenization treatment on microstructure of Bi-Mn-Fe alloy

Effect of homogenization treatment on microstructure of Bi-Mn-Fe alloy was investigated by means of scanning electron microscope(SEM) and energy dispersive spectrometer(EDS).The results show that as-cast microstructure of Bi-Mn-Fe alloy consists of three phases: BiMn、 Mn(Fe) and Bi.For permanent cast Bi-Mn-Fe alloy,Bi distributed discretely in the alloy.For liquid Bi-Mn-Fe alloy quenched in water,Bi distributed continuously in the alloy.The homogenization treatment of Bi-Mn-Fe alloy at 400 ℃ does not change the phase constituent of the alloy.The longer the homogenization time is,the more the amount of BiMn phase.For permanent cast Bi-Mn-Fe alloy,the amount of BiMn phase changed no longer after 16 h homogenization at 400 ℃.For liquid Bi-Mn-Fe alloy quenched in water,the amount of BiMn phase did not change when the homogenization time was longer than 4 h.After homogenization,the morphology of BiMn phase in Bi-Mn-Fe alloy changed from discrete distribution or isolation to continuous distribution.The amount of BiMn phase in Bi-Mn-Fe alloy annealed at 300 ℃ was more than that at 400 ℃ and it changed no longer when the homogenization time exceeded 8 h.