Control of the Alloying Element Distribution in Al-Alloys by High Magnetic Fields

Abstract

The distribution and solidified structure of alloying elements are important for the quality and the properties of alloys. In the present study, the solidification behavior of aluminum-rich alloys is studied under various high magnetic field conditions, and the influences of uniform and gradient magnetic fields with different intensity and direction on the distribution and the morphology of solute elements of Al-Cu and Al-Mg alloys are investigated. It is found that because of the differences of the electromagnetic force (Lorentz and magnetization forces) acting on Cu element and Mg element with different physical properties in the matrix, the regularities of distribution for Cu element and Mg element are opposite just in the intracrystalline and intergranular under high uniform magnetic field condition, and not only the content but the distributions of Cu and Mg elements are obviously different under high gradient magnetic field conditions as well. It can be concluded that high magnetic field has different effect on the solute distribution in alloys with different physical properties such as density, susceptibility, conductivity, etc. And the experimental results indicate that it is possible to control the terminal solubility and morphology of the solute elements in alloys by high magnetic fields.

Effects of high magnetic fields on solidified structures of Mn-90.4 wt% Sb hypoeutectic alloy

“…It is widely recognized that a high magnetic field can exert three effects on a system, that is, Lorentz force, magnetic force and magnetization. On the basis of these three effects, investigations on non-or unidirectional solidification under high magnetic fields have shown that high magnetic fields can induce aligned microstructures [6][7][8]; change the equilibrium partition coefficient [9,10], phase transformation temperature [11,12] and the distribution of solute elements [13,14]; decrease the diffusion coefficient [15,16]; and induce thermoelectromagnetic convection [17,18].…”

Effects of Uniform and Gradient High Magnetic Fields on Gravity Segregation in Aluminum Alloys

“…The measurement for the mean average composition of dendrite cores is given in Ref. 12). Figure 4 shows the changes of C u ϪC l of solutes in Al-5wt%Cu and Al-10wt%Mg alloys as a function of B, respectively.…”

“…The solutes of Cu and Mg for Al-Cu and Al-Mg alloys, respectively, still segregate at the interdendritic regions, although the extent of segregation may be enhanced or reduced by a high magnetic field as mentioned in previous paper. 12) In order to evaluate the gravity segregation of the solute in the alloys, an estimate of the extent of segregation can be made by C u ϪC l , where C u and C l are the average elemental concentrations at the dendrite cores in the upper and lower parts of the specimens, respectively. The measurement for the mean average composition of dendrite cores is given in Ref.…”

“…[7][8][9] The previous studies show that the high magnetic field can affect the solute distribution during solidification process. 8,[10][11][12] Results of experiments using low magnetic fields 13) and numerical modeling 14) indicate that the magnetic field can suppress gravity segregation in term of Lorentz force. The segregation in solidified structure is associated with both the nature of the solute and the magnetic intensity and gradient.…”

Solidified Structure Control of Metallic Materials by Static High Magnetic Fields

“…22) Furthermore, the effect of high magnetic fields on the distribution of solute elements of some alloys was investigated in some literatures. [24][25][26] In some Al-rich alloys solidified in high magnetic fields, 24,25) the concentrations of Cu and Mg solutes in a-Al grains were increased and decreased respectively, 24) while their gravity segregation was both obviously reduced. 25) These changes in the distribution of the solute elements were produced by the Lorentz force and depended on the physical properties of the elements such as density and conductivity.…”