Prakt. Met. Sonderband 46 (2014) 291 
multiphase or Materials Initial phases As-deformed phases [Microhardness (GPa) Reference 
Feq5Cugs | bcc Fe + fcc Cu fcc Cu 3.21£0.03 
Cu-Fe bcc Fe+fcc Cu bee Fe + fec Cu | 4,090.20 
FegsCuss | bcc Fe + fcc Cu bce Fe | 6.23£0.15 
I Cu-Cr Crs7Cua3 bce Cr + fcc Cu bee Cr + fcc Cu | 4.36+0.08 
5 consisting in | cu-co hopCorkeCu co 2740.08 
0 or Cr). The | hcp Co+ fcc Cu _ fecCo | 4.31£0.07 _ 
me where no Pure Cu Cu I fcc Cu fcc Cu 2.03£0.03 
1g parameters Table 1: Overview of HPT deformed multiphase materials presented in this study: 
d by scanning initial and as-deformed phases of the multiphase materials and microhardness 
alysis system values of Cu-Fe [8], Cu-Cr [9] and Cu-Co [10]. 
raction (XRD). 
-ameca® on a The significant grain refinement, which is observed in all investigated materials, induces a 
S 3.4.3 from strong increase of the microhardness in the materials (see Table 1). For example, peak 
s. The sample values of over 6 GPa are measured in the Fe-rich Cu composite material. For comparison, 
r pulse energy the microhardness of pure SPD deformed Cu is also given, which is only about 2 GPa. 
neasurements 
500 g (HVO0.5) 
3.2 CHARACTERIZATION OF BULK NANOCOMPOSITES 
3.2.1 XRD ANALYSIS 
XRD investigations are usually conducted to gather first information about crystal 
structures and occuring phases in the as-deformed conditions. After HPT deformation, 
single phase face-centred cubic (f.c.c.), body-centred cubic (b.c.c.) or a mixture of b.c.c 
dy. The strain and f.c.c. supersaturated solid solutions in the different multiphase systems depending on 
initial coarse- the initial composition are obtained [8-10]. The formation of supersaturated solid solutions 
vily deformed due to the absence of peaks in the XRD pattern of one of the constituents of the material 
"deformation and solid solubility extension levels from lattice parameter changes are frequently 
determined from XRD patterns. However, several factors have to be considered here. 
First, peak shifts due to solid solubility extension might occur together with peak shifts due 
to stacking faults, which are frequently observed in f.c.c. metals deformed by SPD. 
Second, grain refinement and increase in lattice strain due to the heavy deformation 
broaden the peaks significantly and reduce, as a consequence, the height of the peaks as 
well. If the amount of the second phase is small, the corresponding peaks might be 
“absent” in the corresponding XRD pattern and this is no indication for the formation of 
supersaturated solid solution. 
3.2.2 EDX ANALYSIS IN THE SCANNING ELECTRON MICROSCOPE 
EDX analysis in the scanning electron microscope is usually used to obtain qualitative and 
quantitative chemical analyses from coarse grained materials or composite materials with 
large phase dimensions. EDX line scan analysis is performed on a conventional bulk Co- 
Cu specimen and on a very thin specimen (TEM lamella) of the same material to illustrate 
limitations of this analysing technique in the SEM for the characterization of bulk 
hase material nanocomposites obtained by HPT deformation. Fig. 2(a) shows the EDX line scan result of 
tion. the bulk nanocomposite specimen in the SEM. Although Cu and a Co signals can be