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Iron-titanium alloys
378
CURRENT TOPICS.
[J. F. I.
I r o n - t i t a n i u m Alloys. J. LAMORT. (Ferrum, xi, 2 2 5 . ) - - T h e equilibrium diagram of these alloys has been studied by the methods of thermal analysis. Alloys containing up to 24 per cent. Ti were prepared by melting ferro-titanium with mild steel in a kryptol furnace. The liquidus consists of two branches meeting in a eutectic point at 13oo ° C. and a composition of about 13 per cent. Ti. Iron retains about 6 per cent. Ti in solid solution. Microscopic analysis confirms the results of the thermal study, and also indicates the existence of a compound FesTi. Study of the magnetic properties showed that the temperature of the magnetic change is lowered by the addition of Ti. The curve showing the relationship between temperature of magnetic change and the Ti content is practically a straight line running from o per cent. Ti and about 787 ° C. to 21 per cent. Ti and 69°0 C. The presence of nitride and cyanonitride can be recognized readily under the microscope. The effect of additions of titanium to iron and steel most likely depends on whether the Ti exists in the alloy in the metallic state or in the form of nitride. This probably accounts for the variations in the results obtained by different workers in this field. L o c o m o t i v e H e a d L a m p s . J. L. MINICK. (Electr. World, lxiv, No. I4, 6 5 6 . ) - - T h e chief function of a locomotive head lamp is to warn persons on the track ahead that a train is approaching. A lamp having a centre-beam intensity of 500 candle-power can be seen 25 miles away by a person of average height, therefore it will give 25 minutes' warning of the approach of a train running at 60 miles an hour (on a straight track, with nothing to obscure the light ! [abstractot] ). T o prevent blinding persons looking towards the !amp, the intensity of the light should not be higher than 15 or 20 candle-power per square inch of projected area. A 3cx)o-candle-power lamp with a I6-inch reflector will have an intrinsic brilliancy within the maximum value. Second in importance among the functions of a head lamp is its ability to illuminate whistle posts, landmarks, etc., properly. These need not be illuminated with an intensity higher than o.Io foot candle. This intensity will be produced by the side rays from a 5oocandle-power lamp when the marker is about 5o feet ahead of the locomotive. No commercially available lamp will enable an engineer to see a dark object ahead in time to stop his train, as a dark dummy can be seen at night only 5oo feet away when illuminated by an incandescent head lamp of IO,OOO candle-power, and a train containing I2 standard steel coaches running 60 miles an hour cannot be stopped inside of I66O feet with the most m o d e m air-brake rigging, or i235 feet with the electro-pneumatic system now being developed. Attention is also called to the fact that an intense head lamp will hinder flagmen and passing engineers seeing the train classification markers, and may even blot out or alter the color of semaphore signal lamps, etc. Valuable references on tests of and regulations on head lamp intensity were included in the paper.
CURRENT TOPICS.
[J. F. I.
I r o n - t i t a n i u m Alloys. J. LAMORT. (Ferrum, xi, 2 2 5 . ) - - T h e equilibrium diagram of these alloys has been studied by the methods of thermal analysis. Alloys containing up to 24 per cent. Ti were prepared by melting ferro-titanium with mild steel in a kryptol furnace. The liquidus consists of two branches meeting in a eutectic point at 13oo ° C. and a composition of about 13 per cent. Ti. Iron retains about 6 per cent. Ti in solid solution. Microscopic analysis confirms the results of the thermal study, and also indicates the existence of a compound FesTi. Study of the magnetic properties showed that the temperature of the magnetic change is lowered by the addition of Ti. The curve showing the relationship between temperature of magnetic change and the Ti content is practically a straight line running from o per cent. Ti and about 787 ° C. to 21 per cent. Ti and 69°0 C. The presence of nitride and cyanonitride can be recognized readily under the microscope. The effect of additions of titanium to iron and steel most likely depends on whether the Ti exists in the alloy in the metallic state or in the form of nitride. This probably accounts for the variations in the results obtained by different workers in this field. L o c o m o t i v e H e a d L a m p s . J. L. MINICK. (Electr. World, lxiv, No. I4, 6 5 6 . ) - - T h e chief function of a locomotive head lamp is to warn persons on the track ahead that a train is approaching. A lamp having a centre-beam intensity of 500 candle-power can be seen 25 miles away by a person of average height, therefore it will give 25 minutes' warning of the approach of a train running at 60 miles an hour (on a straight track, with nothing to obscure the light ! [abstractot] ). T o prevent blinding persons looking towards the !amp, the intensity of the light should not be higher than 15 or 20 candle-power per square inch of projected area. A 3cx)o-candle-power lamp with a I6-inch reflector will have an intrinsic brilliancy within the maximum value. Second in importance among the functions of a head lamp is its ability to illuminate whistle posts, landmarks, etc., properly. These need not be illuminated with an intensity higher than o.Io foot candle. This intensity will be produced by the side rays from a 5oocandle-power lamp when the marker is about 5o feet ahead of the locomotive. No commercially available lamp will enable an engineer to see a dark object ahead in time to stop his train, as a dark dummy can be seen at night only 5oo feet away when illuminated by an incandescent head lamp of IO,OOO candle-power, and a train containing I2 standard steel coaches running 60 miles an hour cannot be stopped inside of I66O feet with the most m o d e m air-brake rigging, or i235 feet with the electro-pneumatic system now being developed. Attention is also called to the fact that an intense head lamp will hinder flagmen and passing engineers seeing the train classification markers, and may even blot out or alter the color of semaphore signal lamps, etc. Valuable references on tests of and regulations on head lamp intensity were included in the paper.