Abstract
Following to the theory of invar, previously proposed by the present investigator, he has measured the thermal expansion of ternary alloys of cobalt, iron and chromium, and has found that an addition of a small quantity of chromium to cobalt-iron alloys containing more than 50 per cent of cobalt considerably reduces their expansibility. The measurement of the thermal expansion of alloys having small expansibility was made from the temperature of liquid air to the vicinity of the magnetic transformation point, and the range of temperature available for this small expansibility was examined. The smallest coefficient of linear expansion at 20° found in the present investigation was -1.2×10-6. Further, it was found that alloys having small expansibility were practically incorrodible in dilute solution of NaCl. Some physical properties of these alloys were also determined.
