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

摘要

The microdefects, the thermal expansion coefficients and the magnetization -temperature curves of the Fe_(64)Ni_(36-x)Co_x (x=1~10) were characterized by means of positron lifetime, X-ray diffraction, Michelson's interferometer and VSM modular on PPMS, respectively. The Fe_(64)Ni_(30)Co_6 alloy is a mixture of BCC and FCC structures. With the Co content increasing in Fe_(64)Ni_(36-x)Co_x alloys, the BCC phase increases, while the FCC phase decreases. In comparison with other Fe_(64)Ni_(36-x)Co_x alloys, the Fe_(64)Ni_(31)Co_5 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.