Abstract
The influence of addition of 5 per cent of copper on the thermal expansion, the rigidity modulus and its temperature coefficient of alloys of cobalt, iron and chromium has been determined. The relation between the thermal expansion coefficient or the temperature coefficient of rigidity modulus of copper-added alloys and the concentrations is qualitatively similar to that in the case of the ternary alloys of cobalt, iron and chromium, but the relation in the case of rigidity modulus is more complex than in the case of the ternary alloys. The composition at which the thermal expansion coefficient shows its smallest value and the temperature coefficient of the modulus its largest positive value does not show any remarkable change with addition of copper. When copper is added, the concentration range having the positive temperature coefficient of the modulus becomes comparatively narrower. Some elinvar type alloys containing comparatively high chromium have values of rigidity modulus larger than 8×105 kg/cm2, showing an important characteristic for practical application.
