292 Prakt. Met. Sonderband 46 (2014)
clearly distinguished, a rather homogeneous distribution of Cu and Co is visible from 20 at. %
quantitative chemical analysis. Spatial resolution is determined by the penetration and well as
spreading of the electron beam in the specimen (excitation volume). By the use of the very
thin specimen (TEM lamella), the excitation volume is geometrically reduced without
reducing the acceleration voltage and the spatial resolution of the EDX analysis can be
clearly improved. In Fig. 2(b), the EDX line scan obtained in the SEM using the TEM
lamella is shown. The corresponding microstructure of this specimen is shown in the TEM
micrograph in Fig. 1. Distinct regions of high Co and high Cu concentrations, which
indicate Co and Cu phase regions, can be resolved. From the EDX concentration plot, the
width of the Co or Cu phase regions can be estimated to be about 0.6-1.0 um and 0.1-
1.0 um for Co and Cu, respectively. In between the distinct phases, gradients of Cu and
Co concentrations with a relatively large width (~0.1 um) are visible. This is not surprising,
because the spatial resolution of the EDX analysis of the TEM lamella is given by its
thickness (usually ~50 nm thick to be transparent for the electron beam in the SEM).
a) TL =
Cw! Cu
at, „BE
by 16%" a
os Cu
2 ICC
Ha a
0 © 3DAP a
EE a feature
Distance (um commor
Fig. 2: (a) EDX line scan along the dashed line in the SEM micrograph. (b) EDX line material
scan along a thin specimen (TEM lamella) in the SEM. enhance
preparat
is site-s
3.2.3 3DAP ANALYSIS OF BULK NANOCOMPOSITES neglocte
case 0
To obtain information about elemental distribution on the nanometer or even atomic scale magnific
and to determine the exact extent of alloying, 3DAP analysis can be performed. To give an Informat
example, a 2D-composition map of the FesoCuso multiphase material after HPT with a |
deformation is shown in Fig. 3. The distinct high concentration Fe regions indicate that spectros
some areas are rich in Fe whereas others are rich in Cu. Some medium concentration Such in
regions can also be detected. The level of deformation induced interfacial mixing among however
the different phases can be determined by 1D-concentration profiles along selected demand:
interfaces. A Cu as well as a Fe concentration profile across a smaller analysed volume
(16x20x50nm) of the reconstruction is additionally shown in Fig.3. From this plot, grain 4. SUM
sizes in the nanometer range can be determined. Both 1D-concentration profiles exhibits :
distinct gradients which indicate interdiffusion. The mutual solubility of Fe and Cu is B
normally less than 0.1 at. % at room temperature under equilibrium conditions. The Cu ulk nar
concentration and the Fe concentration in the corresponding Fe or Cu phase is over Tultipha