Effect of steady magnetic field on undercooling of Al-Cu alloy melts

Abstract

The undercooling behaviors of three Al-Cu alloy melts in a steady magnetic field (SMF) were investigated by differential thermal analysis. It was found that the nucleation temperatures of primary phases in three alloys gradually shifted to a lower temperature with increasing the SMF intensity, i.e., the undercooling was enhanced in the SMF. The enhanced undercooling mainly results from the increase in the liquid/solid interfacial free energy in the SMF. In addition, the reduction of migration rates of atoms in the liquid phase in the SMF is partially responsible for the increase in undercooling.

Review on Eutectic-Type Alloys Solidified under Static Magnetic Field

“…The magnetic energy can not only influence the temperature of phase transformation [13,65,78] but also the orientation of materials [30,64], which will be shown in the following section.…”

“…DTA data then can be obtained under the SMF. The DTA of an Al-Cu hypereutectic alloy demonstrated a significant decrease in liquidus temperature during the cooling stage under a high SMF [65,113,114] (Figure 9). The decrease of liquidus temperature may be attributed to the increase of nucleation undercooling caused by changing the interfacial free energy, which acts as a barrier for the nucleation event [115].…”

“…Therefore, the aforementioned forces, which have significant effects on the kinetic processes of solidification, are effective in controlling atom diffusion [52][53][54][55][56], nucleation events [42,57], melt convection [19,34], solute distribution [32,58,59], crystal migration [21,43,60], and morphology evolution [61][62][63] during solidification. Apart from kinetic processes, magnetic energy can also modify thermodynamic events, such as phase transformation and crystal orientation, even in a non-ferromagnetic system [12,64,65]. Indeed, the crystal orientation is considered to be influenced by the SMF in both thermodynamic and kinetic ways.…”

Solidification Processing of Metallic Materials in Static Magnetic Field: A Review

“…Typically, a recent work regarding the change in the undercooling of Sn, Al, Zn and three Al-Cu alloy melts in different SMFs was performed by Rui Guo and his co-workers [29][30][31] (Figure 3). They proposed that the change in undercooling is related to the increase in the liquid/solid interfacial free energy and to the reduction in migration rates of atoms in the liquid phase in the SMFs.…”