Al85Ni10La5 (at.%) alloy powders were fabricated using gas atomization. X-ray diffraction analysis revealed that powders in the size range of < 500 mesh (< 25 mu m) are amorphous. The crystallization behavior and kinetics of the amorphous Al85Ni10La5 powders (< 25 mu m) were investigated during continuous heating and isothermal annealing. The amorphous Al85Ni10La5 alloy undergoes a multi-step crystallization reaction in the temperature range of 250-390 degrees C. The activation energies for the first exothermic reactions were determined as 344 kJ/mol. Instead of a primary crystallization, a eutectic reaction was found to be associated with the first reactions and the crystalline phases were identified as fcc-Al, Al11La3, Al3Ni and a metastable phase Al3La. The isothermal annealing was carried out at temperatures of 235 degrees C, 245 degrees C and 250 degrees C. Results from the isothermal annealing analyses revealed presence of quenched-in Al nuclei. The influence of isothermal annealing on the thermal stability of the Al85Ni10La5 powders (< 25 mu m) is also discussed. (c) 2005 Elsevier B.V. All rights reserved.

Nanocrystalline aluminum matrix composites were synthesized via hot extrusion of cryomilled 5083 Al (Al-4.59Mg-0.57Mn-0.25Fe in wt.%) blended with amorphous Al85Ni10La5 Powder. The compression yield strength of the as-extruded composite is 813 and 906 MPa for 10 and 20 vol.% Al85N10La5, respectively. The observed thermal stability is discussed in light of the mechanical behavior. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.