High-field susceptibility of invar alloys

High-field susceptibility of iron-nickel alloys over the entire concentration range has been measured at 4.2 K. The temperature dependence of high-field susceptibility of alloys containing 29.1 and 32.7 at % Ni has been investigated in the temperature range from 4.2 to 150 K. Anomalous temperature dependence of the susceptibility of the alloys investigated can be explained by the existence of an antiferromagnetic phase at low temperatures.