128 Prakt. Met. Sonderband 52 (2018)
2. EXPERIMENTAL WORK La
2.1 MATERIAL iw
For first experiments the equiatomic alloy AI20Cu20Ni20Ti20V20 was manufactured. The ~~ '*
alloy was synthesized in an arc furnace and the received button was five times remelted in
order to homogenize the microstructure. After that, an annealing heat treatment was Fo
performed at 700 °C, 800 °C and 900 °C for 2 h and 20 h in the argon atmosphere for a
further homogenization. Kr
%.-
2.2 CHARACTERISATION OF THE MICROSTRUCTURE AND MECHANICAL fine
TESTING BE
ase
2.2.1 MICROSTRUCTURE WC
Sample preparation for the light optical characterization includes wet grinding by SiC 1
abrasive paper with 180-, 320-, 500-, 800- and 1200-grit and polishing with diamond paste
with 15 pm-, 6 pm- and 1 pm-grit for 5 min respectively. Afterwards the samples were
polished (vibratory polisher) with diamond paste (1 um) and SiO, (0.05 um) and etched in
V2A etchant, in order to reveal the grain size, morphology, and presence of second-phase
precipitates. For the light-optical observations the light microscope Aristomet from Leica
was used. In addition, the hardness measurements were carried out on metallographic
cross sections.
For the determination of the precipitate population, the specimens were investigated by
scanning electron microscope (SEM). In this study a Zeiss Auriga Crossbeam electron and
ion beam microscope with energy dispersive X-ray spectroscopy (EDS) system was used.
The constituents can be observed here with a resolution of up to 1 nm. The SEM
investigations were performed on metallographic cuts. The sample preparation was carried
out in a similar way as for the light-optical investigations.
X-ray diffraction (XRD) measurements were carried out using diffractometer Siemens
D5000.
The needles-like samples for 3D atom probe tomography (APT) investigations were
prepared by the focused ion beam (FIB) method using an FEI Quanta system. The surface
of the sample was coated by Pt for protection, which was deposited with the ion beam of
the FIB. The lift out lamella were cut into pieces, which were attached with Pt on the flat
tops of a multi-tip Si-coupon. The results of the atom probe measurement were performed
by a Cameca LEAP 4000X HR system located at the Karlsruher Nano Micro Facility at the MM
Karlsruhe Institute of Technology in the voltage assisted mode. The coupon temperature a
during the measurements was 50 K. The pulse fraction was set to 20 % with a pulse Hose
frequency of 200 kHz. Hs
To characterize the mechanical properties the compression tests on different material FEN
conditions were carried out at room temperature in air and in hydrogen atmosphere. The in ce
compression tests were chosen due to the small amount of manufactured material iE
necessary for specimen preparation. oe
Can be se
foi:
ot,
Fig 30
AM
