MAGNETIC AND THERMAL-PROPERTIES OF AMORPHOUS AL-GD-TM (TM=FE, CU) ALLOYS

Amorphous aluminium-transition metal-rare earth alloys (Al-RE-TM) with compositions Al65Gd15Cu20 and Al1Gd1Fe1 have been prepared by melt sp inning. X-ray diffraction studies show the average interatomic spacing in these alloys to be about 7% greater than in fcc aluminium and abou t 20% greater than in amorphous Al-TM-Si alloys. Thermal analysis meas urements of the Al65Gd15Cu20 and Al1Gd1Fe1 alloys show the crystalliza tion temperatures to be 647 and 945 K, respectively. Magnetization stu dies show Al65Gd15Cu20 to be paramagnetic with a localized gadolinium moment of 8.0 +/- 0.2 mu(B). Al1Gd1Fe1 shows ferromagnetic behaviour, with T(c) = 275 K and a saturation magnetization of 124 e.m.u. g-1. A room-temperature Fe-57 Mossbauer spectrum of Al1Gd1Fe1 shows a well-de fined quadrupole doublet with a mean splitting of about 0.4 mm s-1. At 77 K, the Mossbauer spectrum shows a well-resolved sextet, correspond ing to a mean iron hyperfine field of 96 kOe.