Morphology and Formation Mechanism of Dendritic Inclusions in Iron and Iron-Nickel Alloys Deoxidized with Silicon and Solidified Unidirectionally

Abstract

Th e morphology of illelusiolls ill Fe alld Fc-Ni alloys. which were deoxidized with O. Iwl % of Si alld solidified ullidirectiollf/lly ullder sllecijied conditiolls, have been investigated. D elldritic illelusiolls were frequently observed ill ingots cOlltaillillg a large amount of O. but hardlj' in illgots whose 0 cOlltellt was smaller than the alllount equilibrating to the amount of Si at the liquidus te mpemture. Th e delldritic illelusiolls were classijied roughly illto two (ypes ,' one is those existillg main!), ill the illtercellular or illterdelldritic regioll of lIlatrix. alld the other is those growlI from a spherical /lrimary illelusioll. B) , electroll IJrobe microallalyses alld selected-area transmission electron diffraction eX/leriments Oil the dendritic inclusions. it was cOllfirmed that they were com/losed of silica or s ilicate and substalltially amorphous. The dendritic illclusiolls seemed to be formed b), a suitable gradiellt if a slifficient degree q(supersaturatioll , which was caused lIIailllj' b), th e segregatioll of 0 alld/or caused by supercoolillg durillg solidification of Fe.

Inclusions in Iron Ingots Deoxidized with Manganese or Silicon-Manganese in an Alumina Crucible and Solidified Unidirectionally

“…The raw material, together with the deoxidizer, was melted at 1 930 K for 10 min with a high-frequency induction of 100 kHz, and was solidified from the bottom by withdrawing the induction heating coil upward at a constant speed of 28.3 ,um/s, under the following two conditions : (1) The induction heating power was gradually increased so that the temperature of the melt might be kept as constant as possible (referred to as "T.C." hereafter) and (2) The induction heating power was kept constant (referred to as " P.C. ").…”

Effect of hafnium and molybdenum addition on inclusion characteristics in Co-based dual-phase high-entropy alloys

“…where v is the molar volume of inclusions (m 3 •mol −1 ), the value of which for Al 2 O 3 is 2.56 × 10 −5 m 3 •mol −1 [36], that for HfO 2 is 2.17 × 10 −5 m 3 •mol −1 [37], and that for MnS is 2.2 × 10 −5 m 3 •mol −1 [38]; σ is the interfacial energy between the matrix and the inclusions; k is Boltzmann's constant (1.38 × 10 −23 J/K); T is the temperature (K); A is the frequency factor (m −3 •s −1 ), the value of which for Al 2 O 3 is 10 32 m −3 •s −1 [39], that for HfO 2 is 10 33 m −3 •s −1 [39], and that for MnS is 10 42 m −3 •s −1 [38]; K and K e are the reaction constant and equilibrium constant of the inclusion formation reaction, respectively.…”