. Transactions. in an electricfurnace, its fluidity becomes less and less as the temperaturebecomes higher. At the melting-point of titanium (whichMoissan has elsewdiere stated to be above 2,500° C.) the con-tent of the crucible has become so viscous that it will notflow easily. If then the temperature is lowered, the bath re-gains its fluidity and flows like water. Wittorff formed theconclusion that the cause of the solidification of the iron-alloys ^ Comptes rendus de VAcademic des Sciences, vol. cxxiv., No. 14, p. 716 (1897). 486 WITTORFF S IRON-CARBON EQUILIBRIUxM DIAGRAM. at very high tem
. Transactions. in an electricfurnace, its fluidity becomes less and less as the temperaturebecomes higher. At the melting-point of titanium (whichMoissan has elsewdiere stated to be above 2,500° C.) the con-tent of the crucible has become so viscous that it will notflow easily. If then the temperature is lowered, the bath re-gains its fluidity and flows like water. Wittorff formed theconclusion that the cause of the solidification of the iron-alloys ^ Comptes rendus de VAcademic des Sciences, vol. cxxiv., No. 14, p. 716 (1897). 486 WITTORFF S IRON-CARBON EQUILIBRIUxM DIAGRAM. at very high temperatures was the crystallization of an endo-thermic iron carbide, and he resolved upon a systematic studyof the hyper-eutectic alloys of iron and carbon. He found akryptol furnace satisfactory up to temperatures of 2,000°;above that heat he found an arc-furnace such as shown in to be the best adapted. A Fery pyrometer was used, andfound to be accurate within a few degrees at the highest Fig. 13.—Wittorffs Electric-.\rc Furnace. His first observations confirmed those of Moissan,. namely,that iron heated in contact with carbon and maintained slightlyabove 2,000° C. rapidly dissolves the carbon and soon becomesentirely solid. On quenching such a solidified melt from 2,119°in snow-water, he found that it contained per cent, ofcarbon. (See Fig. 2.) A similar mass which had been allowedto solidify at the high temperature became liquid upon coolingto 1,370° C As has already been stated, Wittorffs investiga-tions convinced him that the cause of the solidification at hightemperatures was the formation of the endothermic carbide, wittorffs iron-carbon equilibrium diagram. 487 FCgC, and the liquefaction at lower temperatures was due tothe dissociation of this cementite into a liquid phase and monograph also includes a discussion of the meta-stable changes of the alloys, and the work of Goerens, Groerenswith Gutowsky, and Ilanemann, but th
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