Decomposition mechanism in supercooled liquid alloys

摘要

The authors performed small-angle neutron scattering experiments on the bulk211u001eamorphous alloy Zr(sub 41.2)Ti(sub 13.8)Cu(sub 12.5)Ni(sub 10)Be(sub 22.5) 211u001e(Vit1(reg-sign)) and on further alloys, where the ZrTi and CuBe content have been 211u001echanged, following the tie-line in the direction of Zr(sub 46.8)Ti(sub 8.2)Cu(sub 211u001e7.5)Ni(sub 10)Be(sub 27.5) (Vit4(reg-sign)). The SANS data of the samples, 211u001epreannealed at temperatures between 330 C and 390 C, show interference peaks 211u001egiving evidence for spatially correlated arrangements of inhomogeneities. The Q 211u001evalues of the interference peaks, Q(sub max), decrease with increasing annealing 211u001etemperature T(sub a) and, at a given annealing temperature, with composition 211u001efollowing the tie-line from Vit1 to Vit4. They find that, in two distinguished 211u001eregimes, the data follow a relation 1/L(sup 2) (proportional-to) T(sub a) as 211u001epredicted by Cahn's theory (L = 2(pi)/Q(sub max) is the wavelength of the 211u001edecomposition), with a crossover at the glass transition temperature T(sub g) = 211u001e350 C. The authors explain the crossover by different diffusion mechanisms below 211u001eand above T(sub g).