Microstructures and thermal stability of the semi-solid 2024 aluminum alloy prepared using the pulsed magnetic field process: Effects of technological parameters

Microstructure of Al–Mg–Si–La alloy under pulsed magnetic field treatment during solidification

“…The external magnetic field technology act on alloy melt has attracted extensive research attention owing to its many advantages, such as refining grains, reducing segregation of solute elements and improving mechanical properties of alloys. Previous researches mainly focused on the grains refinement mechanism of alloys in the solid-liquid two-phase region under external magnetic field, which mainly consist of 'broken dendrite' effect (dendrites separated from the mould under the electromagnetic force and the broken dendrites become heterogeneous nucleation particles), 'magnetic cooling' effect (magnetic field can affect the undercooling of the melt) and 'magneto-striction' effect (the conductive fluid will shrink to its central axis under the action of the magnetic field) and so on [16][17][18][19][20][21][22][23]. At present, more attention has been paid to the effect of pulsed magnetic field on the liquid metal at the liquid region of the alloy, which has become an effective technique for solidification microstructure controlling.…”

Microstructure of shear-induced thixoformed Al-4.5Cu-1.5Mg alloy via RAP and SSTT processes

“…such as near net shape, low forming efforts, reduction of porosity, increasing mechanical properties, and extending die life [2][3][4][5][6][7][8][9][10][11] . Semi-solid forming technology includes thixoforming and rheocasting [1,5,8,11,12] .…”

“…So to speak, this is important to obtain non-dendritic microstructure [4][5] . There are several methods to create a globular microstructure to be used in the thixoforming process.…”

“…The given liquid fraction can be obtained due to controlling temperature, and time is required to ensure complete transition from dendritic or rosette to spherical structure. Then this material is transferred into a preheated mould [2,5,7,[12][13][14][15] . Thixoforming temperature is the most important parameter, and holding time is the least effective parameter.…”