Nanocrystallization behaviour of Al-Y-Ni with CU additions

This paper reports the results of a short investigation into the effect of Cu additions upon the nanocrystallization behaviour of an Al-Y-Ni alloy. 1 at.% Cu was added to a base alloy of Al88Y4Ni8 either by substitution for A l to form Al87Y4Ni8Cu1 or. by substitution for Ni to form Al88Y4Ni7Cu1 Cons istent with previous findings in the literature. the substitution of Cu for Al was found to increase the thermal stability of the amorphous phase, whe reas the substitution of Cu for Ni was found to decrease its thermal stabil ity. Comparing the microstructures of these alloys after heat treatment to produce equivalent volume fractions of Al nanocrystals showed average grain sites of similar to 14, similar to 12 and similar to9 nm for the alloys Al 88Y4Ni8, Al87Y4Ni8Cu1 and Al88Y4Ni7Cu1, respectively. The effect of Cu in r efining the size of the nanocrystals was attributed to enhanced nucleation increasing the number density of the nanocrystals. rather than diffusion li mited or interface limited growth. Further investigation of this behaviour requires direct characterization of the local partitioning behaviour of the . Cu during crystallization. (C) 2001 Elsevier Science B.V. All rights rese rved.