Stability of ferromagnetism in FCC Fe–Cu–Au alloys prepared by mechanical alloying

We have studied the relation between the stability of ferromagnetism and the atomic volume of FCC Fe–Cu–Au alloys prepared by mechanical alloying by means of X-ray diffraction, magnetization measurement and Mossbauer effect. The atomic volume of the FCC Fe0.5Cu0.5 alloy increased almost linearly with the substitution of Au atoms for Cu from original 12.09×10−3 to 13.31×10−3 nm3 for 40% replacement. The Curie temperature of the alloy also increased in the same manner from 489 to 582 K. It is found that the increase in atomic volume stabilizes the ferromagnetic state of the FCC alloys. The values of magnetic moment of iron in Fe0.5Cu0.4Au0.1 and Fe0.5Cu0.3Au0.2 were estimated to be 2.34 and 2.44 μB, respectively, which are larger than that of α-iron (2.22 μB). The magnetic hyperfine field of iron in Fe0.5Cu0.4Au0.1 showed wide distribution from 22 to 38 T at 82 K, which is probably caused by the variation of species of surrounding atoms of iron.