In an ideal scenario, a phase field model is able to compute quantitative aspects of the evolution of microstructure without explicit intervention. The method is particularly appealing because it provides a visual impression of the development of structure, one which often matches observations. The essence of the technique is that phases and the interfaces between the phases are all incorporated into a grand functional for the free energy of a heterogeneous system, using an order parameter which can be translated into what is perceived as a phase or an interface in ordinary jargon. There are, however, assumptions which are inconsistent with practical experience and it is important to realise the limitations of the method. The purpose of this review is to introduce the essence of the method, and to describe, in the context of materials science, the advantages and pitfalls associated with the technique.

A method using electropulsing to separate inclusions from molten steel is developed, based on the differences in electrical properties between the inclusions and liquid metal. The inclusions have different electrical resistivity from that of the liquid steel and hence being expelled to the surface of the metal by electropulsing. In comparison with the as-solidified untreated steel, the size of the inclusion is significantly larger at the surface of the molten steel due to the enhanced agglomeration. Moreover, the technique is efficient in eliminating particles smaller than 20 µm.

of pearlite are extensively used in various engineering and commercial applications since they possesses a good combination of strength and ductility as well as other useful material properties such as corrosion resistance, wear resistance, weldability and machinability. The stress-strain behaviours of ferritic-pearlitic steels strongly depend on its constituent phases: ferrite governs the ductility whereas pearlite phase controls the strength [1]. The relationship between microstructure and mechanical properties of these steels have been investigated by many researchers [1,2,3]. Various colonies of pearlite have different lamellae orientations. These cementite lamellae are frequently paralleled and curved and the interlamellar spacing varies in size from colony to colony [2]. Hence, pearlite microstructure can be tailored by variation of the interlamellar spacing which directly affects the strength [3].It is known that the application of electric current pulses to metallic materials affects materials plasticity [4], recrystallization [5], structure relaxation [6], casting microstructure [7,8] and fatigue life [9]. For Fe-3wt% Si alloys, electropulse has been found to promote the Goss-texture development during recrystallization [11,23]. Theoretically, electropulse is found affecting the kinetic barrier and free energy sequence of phases. The former includes the phase transformation at a lower than ordinary temperature [12] and the enhanced diffusivity [17]. The latter includes the electropulseinduced new phase [14] and new microstructure formations [15]. In the present work, electropulse-induced cementite plates rotation in ferritic-pearlitic steel was observed. This reveals a new mechanism that has not been covered in literature. Application of Electropulsing in the process of ferritic-pearlitic steel may provide a new way to enhance mechanical properties by altering the pearlite transformation and microstructure.The steel was prepared via the conventional ingot metallurgical routine and the chemical composition in weight percentage of the alloy was found to be 0.14 C-1.0 Si-2.1 Mn-0.03 Al-0.025 Nb and balance iron. The ingot was rolled at 800• C to Preprint submitted to Elsevier April 27, 2015 a sheet with 2.64 mm thickness and then chilled slowly in furnace. Its microstructure at ambient temperature consists of mainly the polycrystalline ferrite grains and a small amount of cementite scattered among the ferrite. The sheet was cut into many 30 mm(longitudinal length) × 3.42 mm (width) × 2.64 mm (thickness) samples and grouped randomly for subsequent electropulsing treatment. The electropulse was generated by an Avtech AV-108F-B-P Current Pulser which converted the direct current into pulsed current. The direct current power source has standard output power of 80 watts and standard output electric potential of 20 volts. The pulse width, peak current intensity, pulse frequency and pulse trigger mode are programmable. The testing steel sample was connected with two copper electrodes from both ends to form a curr...

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