Solid-state reactions in binary mixtures of nanometer-sized particles

Solid-state reactions in mixtures of nanometer-sized Cu and Zr as well as Ni and Zr crystallites—produced by inert-gas condensation followed by in situ compaction—have been investigated by x-ray diffraction and thermal analysis. Nanocrystalline particle mixtures and multilayered samples showed qualitatively the same behavior: A solid-state amorphization reaction occurs in NixZr1−x samples but not in CuxZr1−x. The results are discussed in the framework of a heterogeneous nucleation and growth process for the amorphous phase. Comparison with results from ball-milling experiments and mechanically prepared multilayers reveals the significance of additional external driving forces.