Using electric current to surpass the microstructure breakup limit

Abstract

The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones.

Study of microstructure and mechanical properties of friction stir welded ferrite-martensite DP700 steel

“…The rods at different orientations will cause different temperature rising when the electric current is passing by. This agrees with our other published calculations [19].…”

“…In our previous study, a torque has been discovered in the calculation of the effect of electric field on the disclike particles [19]. The magnitude of the torque is significant even when the electric field gradient is in a scale of 1 v/cm.…”

Achieving the Control of Nonmetallic Inclusions Morphology and Orientation by Electric Current

“…[22,23] Furthermore, MnS inclusions are refined and spheroidized by electric current pulse in molten steel. [24] The numerical calculation shows that the elliptical disk particle with a lower conductivity than liquid tends to rotate in the direction of the electric current, [25] whereas the particle perpendicular to the current direction tends to break into smaller ones. [26] In fact, aggregation and collision of nonmetallic inclusions inevitably occur in the molten metal.…”

Manufacture of materials using external fields

“…Todorov reports the micro-scale theory of the effect of electric current in bulk materials [10]. Related presentations on the effect of electropulsing on droplet breakup [11] and on low temperature crystal rotation [12] have also been published.…”