Effect of annealing temperature on the structure and mechanical properties of mechanically alloyed AlMg-Nb2O5 and AlMg-ZrSi2 composites.
Mechanical alloying and hot extrusion method were used for manufacturing AlMg-based composites reinforced with addition of niobium oxide (Nb(2)O(5)) and zirconium silicide (ZrSi(2)) particles. High mechanical properties of the materials were found to result from heavily refined structure of composites. It was found that the composite structure was transformed at high temperature as a result of irreversible chemical reaction between disperse reinforcements and surrounding matrix. Chemical reaction for AlMg-Nb(2)O(5) composite results in a growth of intermetallic grains of Al(3)Nb type and very fine oxides particles of 5-20 nm in diameter. In the annealed AlMg-ZrSi(2) composite, new grains of Al(3)Zr, Mg(2)Si and Al(Mg)O are formed as a result of zirconium silicide decomposition. Hot compression tests were performed at constant true strain rate of 5.10(-3) s(-1) within the temperature range of 293-823 K. The high flow stress values are attributed to highly refined structure of the materials that essentially did not coarsen in spite of high deformation temperature.
Kula
A
A
AGH University of Science and Technology, Cracow, Poland. kula@agh.edu.pl
Blaz
L
L
Kaneko
J
J
Sugamata
M
M