Prakt. Met. Sonderband 46 (2014) 289 
NEW CHALLENGES TO CHARACTERIZE BULK 
NANOCOMPOSITES 
B-Gehalt der ) 
sammenhang A. Bachmaier, C. Motz 
ntell validiert Chair of Materials Science and Methods, Saarland University, Saarbriicken, Germany 
,,B) mit einer 
us ergibt sich 
sen, wie zum 
en durch die ABSTRACT 
treten jedoch 
auf, die die Bulk metallic nanocomposites have been obtained by severe plastic deformation (SPD) in 
onnen. Diese different immiscible multiphase systems. Microstructural characterization of conventional 
jedoch nicht coarse-grained composite materials can easily be conducted by standard analysis 
ich mit der techniques like optical microscopy, x-ray diffraction and scanning electron microscopy. If 
selemente Si, phase dimensions and structural sizes of the corresponding phases of multiphase 
“igenschaften materials are refined to the nanometer scale, state-of-the-art characterization techniques 
with high-resolution capabilities are required. Another challenge evolves from the possible 
formation of supersaturated solid solutions in these nanocomposites, hence not only 
structural information is needed but also chemical composition at the nano-scale. 
Transmission electron microscopy as well as atom probe tomography investigations are 
needed to study the evolving non-equilibrium nanostructures and the distribution of the 
ISA different phases on the nanoscale. Specimen preparation for transmission electron 
st ductility microscopy and atom probe tomography raises further difficulties. 
d with boron. 
anced 
)11.04.018 1. INTRODUCTION 
tions of 
Nanocrystalline (nc) materials possess unique mechanical and functional properties, which 
ng of are often enhanced or even completely different from the ones of their coarse grained 
als Science counterparts [1]. During the last couple decades, extensive research has been conducted 
considering the production of nc materials as well as their properties. One such production 
-C-B Hard method for nc materials is high-pressure torsion (HPT), which belongs to the group of 
severe plastic deformation (SPD) methods [2,3]. Typical grain sizes in single phase 
1d, B Alloys materials are between 150-300 nm after HPT [4,5]. HPT deformation of multiphase coarse 
grained metals lead to bulk nanocomposites with a grain size well below 100 nm [6-10]. 
Abrasion. Due to kind of mechanical alloying in bulk form during the HPT process, the formation of 
supersaturated solid solutions or even amorphization reactions can occur in such alloy 
In. Springer, systems with positive heat of mixing [6]. For example, the formation of supersaturated 
solid solutions for many normally immiscible systems (Cu-Fe, Cu-Cr, Cu-Co. etc.) has 
already been observed after HPT deformation [7-10]. 
ral To investigate the as-deformed nanostructures and to evaluate the possible formation of 
lifferent Supersaturated solid solutions, accurate structural characterization on the nanoscale is an 
essential requirement. Due to the nanometer-sized distances of the structural features and 
comparative spacing of the individual phases, the characterization of these materials is a challenging 
3 and issue. State-of-the-art high-resolution characterization techniques like atom probe 
tomography are required to determine, for instance, the exact extent of alloying in the 
formed solid solutions. This study focus on characterization of the above described