THE EFFECT OF CU ADDITION ON THE FORMATION OF FCC-AL PHASE IN RAPIDLYQUENCHED AL-Y-NI ALLOYS

The structure and microhardness of amorphous and nanocrystalline melt- spun Al88Y3Ni9-xCux (x = 0, 2, 4, 6 at.%) alloys were examined. Variat ion of cooling rate controlled by the rotational wheel speed (15-60 s( -1)) resulted in the formation of ductile nano-composite material (x = 2, 4) composed of nanoscale f.c.c.-Al particles embedded in an amorph ous matrix. The effect of replacement of Ni by Cu on structural and me chanical properties was studied. This replacement extended the tempera ture region in which the Al phase precipitates, causing a decrease in particle size from 50 (x = 0) to 10 nm (x = 4). The volume fraction of the nanoscale particles and lattice parameter of Al phase were calcul ated. Due to the nanoscale Al particles, a significant increase in mic rohardness compared with the amorphous single phase was observed. (C) 1997 Elsevier Science S.A.