The influence of iron addition on the crystallisation behaviour of Zr65Al7.
5Cu17.5Ni10 bulk metallic glass was investigated by differential scanning c
alorimetry, (DSC), X-ray diffraction, (XRD), transmission electron microsco
py, (TEM) and magnetisation measurements. The amorphous Zr65Al7.5Cu17.5Ni10
alloy crystallises eatectically into CuZr2 and Zr6NiAl2. Addition of iron
in amorphous (Zr65Al7.5Cu17.5Ni10)(100-x)Fe-x (0 less than or equal to x le
ss than or equal to 20) leads to a changed crystallisation sequence and to
the formation of nanocrystals. The formation of a cubic NiTi2-type Phase (S
.G. Fd (3) over barm, a(0) = 1.22 nm) is the first step of crystallisation
in amorphous alloys with iron contents x greater than or equal to 1. Depend
ing on the iron content the average crystallite size decreases to the nanom
eter regime. Ultrafine nanoclusters of down to 2 nm in size are formed as t
he first step of crystallisation for amorphous Zr52Al6Cu14Ni8Fe20 due to a
high nucleation rate combined with a low growth velocity. The clusters grow
by Ostwald ripening during isothermal annealing up to 5 nm average crystal
lite size. The magnetic behaviour of the (Zr65Al7.5Cu17.5Ni10)(100-x)Fe-x a
lloys is dominated by temperature-independent Pauli paramagnetism for x les
s than or equal to 15. For x = 20, a small contribution of magnetic cluster
s is observed. These ferromagnetic clusters are in accordance with statisti
c composition fluctuations within the homogeneous amorphous phase. With the
formation of nanocrystals the size of the magnetic clusters increases to t
he same order of magnitude.