Prakt. Met. Sonderband 52 (2018) 129
3. Results and Discussion
3.1. MICROSTRUCTURE
Ufacyy
168 ll 3.1.1 METALLOGRAPHIC INVESTIGATIONS
in
Teatm
is 8 The hardness measurements (HV1) of all specimens were performed on the
fr metallographic cross sections. The hardness of the initial condition (as-cast) was found to
be HV1 = 544. The annealing of the sample at 700 °C for 2 h, at 800 °C for 20 h and at
900 °C for 20 h successively decreases the hardness that hints to a more homogenous
HECHANIC microstructure with an even better ductility. The hardness after annealing at 900 °C for
A 20h decreased up to HV1=483. Fig. 1 shows microstructure of different specimens after
heat treatment. One recognizes different areas with segregations and relatively coarse
phases. These constituents could not be dissolved even during the long time annealing at
900 °C. The annealed areas shown at higher magnification present a phase with a fan-like
nding by shape. After the heat treatment at higher temperature (900 °C), this phase tends to be
fim, ye coarser than after the heat treatment at 800 °C (Fig. 1c and Fig. 1e).
stg
Samples were
and etched jy
Second-phage
Tet from Leica
metallographic
vestigated by
m electron and
BM Was Used.
m. The SEM ;
DM Was carried
eter Siemens
‘gations were
n. The surface
€ 10 beam of
Pt on the flat
jae Fig. 1: OM images of different specimens of Al20Fe20Ni20Ti20V20 after heat treatment at
oe a) 700 °C for 2h; b) 800 °C for 20 h; c) detail form b; d) 900 °C for 20 h; e) detail form d
haps 3 45 SEM AND XRD INVESTIGATIONS
oe nae First SEM results show a rather complex microstructure consisting of two main phases
asphere. : (solid solution and coarse V-rich phase) and two other phases in only small volume
ured Maer fractions (Cu- and Cu-Ti-rich phases), which may dissolve during a proper annealing
treatment (Fig. 2a und Fig. 2b). In addition to the coarse V-rich phase, very fine particles
can be seen in the matrix. Furthermore, regular precipitations are visible this coarse phase
(Fig. 2c and 2d). Fig. 3 shows the EDS element mappings with V and Cu distribution which
uniquely identify V- rich phase (Fig. 3b) as well as some isolated particle of Cu-rich phase
(Fig. 3c). Moreover, it can be seen that near the coarse particles vanadium has been
completely removed from the matrix. EDS results averaged over a large areas of the alloy