Young’s modulus of pure ruthenium decreases from 417 GPa [1] to approximately 325 GPa 
for x-Ru solid solution in this work, showing the influence of alloying with aluminum. Young’s 
modulus of RuAl lamellae determined in this work (E = 344 GPa for as-cast condition and E = 290 
GPa in heat treated condition) is higher when compared with the results of Fleischer et al.(E = 267 
GPa [1]). This could be explained by the different methods of investigation and the effect of very 
fine lamellar structure, which additionally increases the stiffness. 
Results from AFM determination of nanohardness are shown in Fig. 5. The hardness 
decreases after homogenization and in RuAl phase follows the sequence: NH > NH lamellae 7 
NH, ....; while the hardness of -Ru lamellae and hallos is the same. Hardness of -Ru lamellae 
(15.6 GPa) is slightly higher, than in RuAl lamellae (14.3 GPa). Similar to Young’s modulus, the 
values of hardness are somewhat higher when determined with greater force (300 uN). 
Despite different mechanical properties of individual phases, due to high interface density of 
fine eutectic structure, a joint action of individual phases produces the effect which results in good 
overall mechanical properties. Compression tests that were conducted at room temperature showed 
that failure occurs after 23 % of deformation. 
Conclusions 
After AFM determinations of local mechanical properties and surface profiles of different 
microscopical features in eutectic Ru-Al alloy, the following conclusions can be drawn: 
1) RuAl phase shows intrinsic deformability when compared to o-Ru phase. 
2) Young’s modulus is affected by heat treatment, in terms that it decreases after homogenization. 
It is also affected by morphology of investigated phases, decreasing in following sequence: in 
RuAl phase E lamellae > E rods > E dendrites and in a-Ru phase: E halos > E lamellae. RuAlE lamellae > oRuE 
lamellae, 
3) Nanohardness also depends on heat treatment and phase morphology. It decreases after heat 
treatment and in RuAl phase follows the sequence: NH, >NH _>NH NH of y- 
Ru lamellae and halos is the same. «ReNH | ~>RAINH 
References: 
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[6] W.C.Oliver, G.M.Phar, J. Mater. Res., Vol. 7/6, pp. 1564-1583 (1992). 
[7] A.S.Darling, Int. Metall. Rev., review 175, Vol. 18, pp. 91-122 (1973). 
[8] D.C.Lu, T.Pollock, Mat. Res. Soc. Symp. Proc. Vol. 552, 1999. Materials Research Society 
KK7.11.1-11.5. 
[9] Atlas of stress-strain curves, H.E.Boyer ed., ASM INTERNATIONAL, Materials Park Ohio, 
1990. 
[10]M.Goken, M. Kempf, Acta Mater., Vol. 47/3, pp. 1043-1052 (1998). 
[11]M.Go6ken, M. Kempf, M.Bordenet, H.Vehoff, Surf. Interface Anal.,Vol. 27, pp 302-306 (1999). 
Acknowledgement 
The authors greatly acknowledge financial support from DFG Graduiertenkolleg project #: III GK 
GRK 232/2, “Neue Hochleistungswerkstoffe fiir efficiente Energienutzung”. 
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