Stability of amorphous Cu/Ta and Cu/W alloys Academic Article uri icon

abstract

  • Although both the Cu/W and Cu/Ta alloy systems are known to be immiscible, the response of coevaporated amorphous films of a-CuxW1x (x=0.450.72) and a-CuxTa1x (x=0.100.55) alloys to thermal annealing and ion irradiation is very different. Alloys of a-CuxTa1x crystallize between 600 and 800C, with the crystallization temperature increasing with Ta concentration, while a-CuxW1x alloys crystallize below 200C. Likewise in Xe- and Ne-ion irradiation studies, a-Cu/Ta can still be observed after 13 displacements per atom (DPA), whereas a-Cu/W alloys completely transform to solid solutions after 0.08 DPA. The results of this study, in combination with previous investigations of amorphous alloys of immiscible systems, show that the crystallization temperature Tc is not predicted equally well for systems with a positive or negative heat of formation. It appears that the kinetic model of crystallization only applies if the transformation proceeds through long-range diffusion. Amorphous alloys which have a positive heat of mixing are predicted to undergo a polymorphic transformation at lower temperatures.

published proceedings

  • Journal of Applied Physics

author list (cited authors)

  • Nastasi, M., Saris, F. W., Hung, L. S., & Mayer, J. W.

citation count

  • 126

complete list of authors

  • Nastasi, M||Saris, FW||Hung, LS||Mayer, JW

publication date

  • October 1985