INTERFACIAL OBSERVATIONS OF NI NI3SI AND NI/NI3GA DIFFUSION COUPLES/

Microstructural observations and selected-area electron diffraction an alyses are conducted around the diffusion-couple interfaces of Ni/Ni3S i and Ni/Ni3Ga. The Ni-rich solid solution phase (gamma phase) grows t owards the Ni3Si- or Ni3Ca-based intermetallic phase (gamma' phase) du ring diffusion annealing and there exists the same crystallographic or ientation relationship between the gamma and gamma' phases. It is demo nstrated that this growth process and structural faeatures are charact eristic of the diffusion couples between pure Ni and Ni-based intermet allics with the Ll(2)-type crystal structure. It is shown that the foc used-ion-beam cutting technique is a useful tool for preparing thin sp ecimens for transmission electron microscopy.