Faceted growth of primary Al2Cu crystals during directional solidification in high magnetic field

Abstract

The high magnetic field is widely used to modify the crystal morphology. In this work, the effect of the magnetic field on growing behavior of faceted crystals in the Al-40 wt. %Cu alloy was investigated using directional solidification technique. It was found that the faceted growth of primary Al2Cu phase was degraded and the primary spacing was reduced upon applying the magnetic field. Additionally, the length of the mushy zone first decreased and then increased with increase of the magnetic field intensity. The quantitative analysis reveals that the shear stress induced by the fluid motion is insufficient to break the atom bonds at the solid-liquid interface. However, both of the thermoelectric magnetic convection (TEMC) and the thermoelectric magnetic force (TEMF) cause dendrites to fracture and reduce the primary spacing. The two effects also weaken the faceting growth. Moreover, the instability of the solid-liquid interface is generated by the TEMF, which further leads to degrade the faceted growth. The length of mushy zone was changed by the TEMC and reached the minimum in the magnetic field of 0.5 T, which is in good agreement with the predicted value (0.83 T).

Review on Eutectic-Type Alloys Solidified under Static Magnetic Field

“…Authors suggested that the TEM effect altered the interfacial energy and led to modifications in the solidification microstructure and orientation relationship [46]. In hypereutectic alloys, the effect of an SMF was similar to that observed in hypoeutectic alloys, as shown in Figure 5c [105]. Transverse SMFs triggered inclined solid-liquid interfaces and accelerated segregation, but an external electric current was applied to the sample to induce an electromagnetic (EM) convection, which counteracted the TEM convection and weakened the destruction of solidification microstructure caused by the TEM effect (Figure 5(d1-d3)).…”

Effect of a High Magnetic Field on Crystal Growth in the Solidification of Hypoperitectic Zn–Ag Alloy

“…In the past two decades, the domain of applying a high magnetic field (HMF) to materials processing has undergone extremely rapid growth since the development of superconducting magnet technology. − Especially in the solidification process of materials, HMFs have exhibited a special capacity to modify the crystal growth and thus the final microstructure and crystallography because of the induced Lorentz force, magnetic torque, magnetization energy, etc. − Morikawa et al obtained aligned primary dendrite arms of MnBi along the HMF direction in the Bi–Mn alloy. Liu et al reported a decrease of the secondary dendrite arm spacing by the HMF in the solidification of Al–Li alloy.…”