Studies of Microdefects, Thermal Expansion and Magnetic Properties of Fe-Ni-Co Invar Alloys

The microdefects, the thermal expansion coefficients and the magnetization -temperature curves of the Fe64Ni36-xCox (x=1~10) were characterized by means of positron lifetime, X-ray diffraction, Michelsonu0027s interferometer and VSM modular on PPMS, respectively. The Fe64Ni30Co6 alloy is a mixture of BCC and FCC structures. With the Co content increasing in Fe64Ni36-xCox alloys, the BCC phase increases, while the FCC phase decreases. In comparison with other Fe64Ni36-xCox alloys, the Fe64Ni31Co5 alloy has a rather high magnetization at temperature lower than Tc, a relatively large change of the magnetization with the temperature near Tc, and a rather low thermal expansion coefficient.