高温での鉄の線膨張率及び比抵抗の測定

抄録

A simple method for measuring the temperature dependence of linear expansion coefficient and specific resistance of iron wire at high temperatures is shown.
The iron wire on the middle point of which a small weight is set is stretched horizontally between two fixed points and is heated directly by d. c. supply. The amount of the sag due to the elongation of the wire as well as the potential drop between the two ends caused by the heating current are observed with which the linear expansion coefficient α and the specific resistance ρ of the iron are obtained.
The experimental results show that a remains constant in the temperature ranges from 1000°C to A₃-point and from A₃-point to 700°C, and has a discontinuity at A₃-point.
It is also found that the temperature dependence of ρ varies anomalously at A₂-transition point. Any anomalous variation was not observed at A₃-transition point.