(t) """'The point where reactions (1) and (2) gave way to reaction (3) was wherethe Si-content in the ingot reached levels equivalent to those present in the electrode.Hence, while reactions (1) and (2) were operating in the ESR-system spinel phases were precipitated; at Si02-activities higher than those given by 12-140/0 Si02 in slags, where the reaction (3) operates, anorthites were precipitated.It was also established that low CaF2-content slags with the critical ranges of CaO-, A1203-and Si02-activities promote exchangereactions such as:~+ (FeO)=CaO + Fe(1) """"" """"" (4) 3Fe (1) Results of these expeiments in terms of average inclusion composition (in at"/o) are given in the following (6) 4340 (7) 4340 (8) 4340 (9) Fe (2) Fe (3) Fe (4) 4340 (10) 4340 (1 l Fig. 2). In the deoxidation range of l0-14 kg t~1, there is a suddenchange in both Al (O.03-0.180/0)

SynopsisThe mechanisms of deoxidation in the electroslag remelting process have been studied, with particular reference to the reactions involving calcium. ESR ingots made with varying deoxidation rates have been examined with respect to their bulk composition and oxide inclusion composition. We find that at high oxygen potentials (% FeO> 0.7 in the slag), reactions between slag FeO and the deoxidant predominate. At low oxygen potentials (% FeO C 0.2 in the slag) exchange reactions between deoxidant and the slag components control the inclusion composition. At intermediate oxygen potentials, the inclusion composition is strongly influenced by the Si02 content of the slag. The manufacture of low-oxygen, low-sulphur steels by ESR will hence require slaps with small contents of both Si02 and A1203.

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Synthesis of intermetallic PbSe induced by high-energy ball milling has been studied. Systematic analysis of transformation in the resulting phases of milling from 0 to 10 h has been traced by characterizing the microstructures in terms of morphology, crystallite size, and percentages of phases formed as a function of milling time. Results reveal the formation of two phases. Where the system of PbO-Se transforms gradually to PbSe. Complete transformation is achieved after 10 h of milling time. Study of particle structure by the Rietveld Method further corroborates the value of the nano-order crystallite diameters as evaluated from the microscopic studies.