Publications in Scientific Journals:

M. Balog, J. Nagy, F. Simancik, K. Izdinsky, G. Requena:
Reviews on Advanced Materials Science, 18 (2008), 415 - 421.

English abstract:
Ultra-fine, monocrystalline, gas atomized Al 99.7% powder was consolidated into profiles
by means of direct extrusion. Conventional approach, with complicated (i.e. expensive) procedure
steps of powder degassing and encapsulating, was avoided. Structural stability of compacts
and enhanced mechanical properties, predominantly those at elevated temperatures, were
of paramount interest. Extrusion yielded sound profiles with ultra-fine grained (UFG) microstructures
of fcc-Al matrix reinforced with homogenously redistributed α-alumina dispersions. Nanoscale
dispersions, originated from torn surface oxide´s envelopes, effectively acted as dislocation
movement and grain growth barriers. Microstructures were found to be intact to long term high
temperature exposures. Relatively high tensile strengths (Rm up to 310 MPa) accompanied with
good ductility (A10 ~10%) and impact fracture toughness (KC ~45 Jcm-2) were determined at room
temperature. Due to unique structural stability no pronounced strength decline was observed and
compacts retained their relatively high strength even at testing temperatures of 500 °C (~70 MPa).
Simple consolidation route without prior degassing resulted in the structure containing micropores
filled with entrapped and compressed gasses. These pores had no negative effect on room temperature
mechanical properties, though expansion of entrapped gases may lead to the reduction
of high temperature ductility.

Created from the Publication Database of the Vienna University of Technology.