Abstract
Young's moduli of elasticity of annealed iron-cobalt and iron-nickel alloys have been measured by the method of magnetostrictive oscillation at ordinary temperatures. In iron-cobalt system, the modulus vs. composition curve shows two maxima at about 25_??_30 and 60 percent and a conspicuous minimum at about 50 percent cobalt in the α-solid-solution range, and moreover makes a minimum in the composition range where the α and γ solid solutions co-exist. The modulus, then, recovers rapidly in the γ-solid-solution range (80_??_95 percent cobalt), but in the narrow range of ε solid solution it seems to decrease. The curve for iron-nickel system shows a linear and rapid decrease in the α-solid-solution range and in the higher composition range where the α and γ solid solutions co-exist, and it makes α minimum at about 40 percent and a maximum at about 85 percent nickel in the γ-solid-solution range.
Further, according to the results of measurements of the densities at the room temperature of these two binary alloys, the density vs. composition curves show a parabola-like increase in both composition ranges of α solid solution of iron-cobalt system and γ solid solution of iron-nickel system and moreover anomalous changes at their boundaries.
