Hakaru Masumoto and Hideo Saito
The mean temperature coefficient of rigidity modulus in the temperature range of 20° to 50° of the alloys of cobalt, iron and chromium containing 50 to 90 percent of cobalt and less than 20 percent of chromium has been measured by a torsion pendulum method. The temperature coefficients of most alloys are negative, while as the concentration approaches the composition of stainless invar (Co=54%, Fe=36.5%, Cr=9.5%), the coefficient diminishes, first gradually and then rapidly,becomes zero at a certain composition and then changes its sign. Then the coefficient reaches a conspicuous positive maximum (+35.9 × 10-5) at the concentration of stainless invar. Thus, there are various alloys having zero coefficient which are called Co-elinvar. These results are almost similar to the case of the temperature coefficient of Young's modulus measured previously by the present investigators, except that in the case of the rigidity modulus, the range showing positive coefficient and the positive maximum is located in the concentrations of more cobalt and less chromium than in the case of Young's modulus.
Further, the rigidity modulus at 20° of the alloys has also been determined with the result that the modulus shows a maximum value (9.34 × 105 kg/cm2), in the alloy containing 50 perccnt of cobalt and 5 percent of chromium and a minimum (5.92 × 105 kg/cm2) in that containing 65 percent of cobalt and 8 percent of chromium.
Please do not copy without permission.