Y ferrites

Many metallurgists, however, incline to the view that jS ferrite is really a solid solution of y in a ferrite 2 in other words, the assumption is made that when iron cools below A3 the conversion of y ferrite into a ferrite is not quite complete, a few y molecules remaining dissolved in the a until the A2 point is reached, at which point the transformation is completed, a ferrite alone remaining.3... 

Carbon readily dissolves in y ferrite, is soluble to a slight extent in fi ferrite, but is practically insoluble in a ferrite. 

Abe, M., and Tamura, Y, Ferrite plating in aqueous solution new technique for preparing magnetic thin film, J. Appl. Phys., 55, 2614, 1984. 

M.A. Alario-Franco, J.M. Gonzalez-Calbet and M. Vallet-Regi, Microdomains in the CaFexMni-xOs-y ferrites. /. Solid State Chem., 65 (1986) 383-391. 

In JEj P -iSbare represented the eqjjilihi im.j elatiQns for S-ferrite, determined by Ruer and Goerens. In this diagram, represents the transition point for 8- and y-ferrite (1400° C.). This Sransitiompoint is greatly raised by addition of small amounts of carbon, as indicated by the curve DE, until at the point E, when the amount of carbon is about 0 i per cent., the transition point lies at 1487 , and the transition curve ends in the curve of complete solidification, AE- This... 

The area ADE represents the region of stability of 8-ferrite the area DEF the region in which 8-ferrite solid solutions and y-ferrite solid solutions are in equilibrium and the area AEB is the area for 8-solid solutions and molten mixtures. 

It has already been mentioned that y-ferrite undergoes transformation into a-ferrite at about 900°. This transition point is represented... 

ASTM A763, Practice Y Ferritic stainless steels Intergranular attack associated with Cr carbides or nitrides... 

Alario-Franco, M.A., Gonzdlez-Calbet, J.M., and Vallet-Regi, M., Microdomains in the CaFexMn, x03.y ferrites, J. Solid State Chem., 1986, 65, 383-91. 

M. Takano, N. Nakanishi, Y. Takeda, and T. Shinjo, in H. Watanabe, S. lida, and M. Sugimoto, eds.. Ferrites, Proceedings of the 3rd International Conference on Ferdtes (lCF-3), Center for Academic Pubhshing Japan, Tokyo, 1981, p. 389. 

Iron (qv) exists in three aHotropic modifications, each of which is stable over a certain range of temperatures. When pure iron free2es at 1538°C, the body-centered cubic (bcc) 5-modification forms, and is stable to 1394°C. Between 1394 and 912°C, the face-centered cubic (fee) y-modification exists. At 912°C, bcc a-iron forms and prevails at all lower temperatures. These various aHotropic forms of iron have different capacities for dissolving carbon. y-Iron can contain up to 2% carbon, whereas a-iron can contain a maximum of only about 0.02% C. This difference in solubHity of carbon in iron is responsible for the unique heat-treating capabilities of steel The soHd solutions of carbon and other elements in y-iron and a-iron are caHed austenite and ferrite, respectively. 

Ferrite (or a) is the low-temperature form of iron. On heating, it changes to austenite (or y) at 914°C when it is pure, and this form remains stable until it reaches 1391°C when it changes to d-iron (if you have forgotten this, check back to p. 319). The phase... 

Sintered and sprayed ceramic anodes have been developed for cathodic protection applications. The ceramic anodes are composed of a group of materials classified as ferrites with iron oxide as the principal component. The electrochemical properties of divalent metal oxide ferrites in the composition range 0- lA/O-0-9Fe2O3 where M represents a divalent metal, e.g. Mg, Zn, Mn, Co or Ni, have been examined by Wakabayashi and Akoi" . They found that nickel ferrite exhibited the lowest consumption rate in 3% NaCl (of 1 56 g A y at 500 Am and that an increase in the NiO content to 40mol 7o, i.e. O NiO-O-bFejO, reduced the dissolution rate to 0-4gA y at the expense of an increase in the material resistivity from 0-02 to 0-3 ohm cm. 

Fig. 11.10 Anodic polarisation of 5-ferrite and Y-austenite showing potential ranges for etching and eleciropolishing. Stainless-type steels in S tio sulphuric acid (after Cihal and...

Cheng, P., Li, W., Zhou, T., Jin, Y., and Gu, M. (2004) Physical and photocatalytic properties of zinc ferrite doped titania under visible light irradiation. Journal of Photochemistry and Photobiology A Chemistry, 168 (1-2), 97-101. 

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