Segregation-induced grain boundary premelting in nickel-doped tungsten

High-resolution transmission electron microscopy and Auger spectroscopy have revealed the formation of nanometer-thick, Ni-enriched, disordered, grain boundary layers in Ni-doped W specimens at 95 degrees C below the bulk eutectic temperature. The stabilization of subeutectic liquid-like grain boundary cores in this model two-component metallic alloy is phenomenologically analogous to the long-sought phenomenon of grain boundary premelting. The existence of such disordered nanostructures at metallic grain boundaries provides insights to resolve several long-standing controversies in interpreting the unique grain boundary diffusion/migration kinetics and mechanical properties for this system, and can have technological importance for a broader range of materials. (c) 2005 American Institute of Physics.