Published online by Cambridge University Press: 26 February 2011
The precipitation behaviour of the transition metals Co, Ni, Cu and Pd has been studied by means of conventional and high - resolution electron microscopy. Special experimental conditions for specimen preparation were chosen, which lead to the formation of haze. These conditions were the same for all metals. Therefore, a direct comparison of the respective precipitation phenomena was possible. Co and Ni were found to precipitate as Si - rich silicide particles exhibiting various morphologies attributed to different stages of particle growth and ripening. It is shown that the generation of Si- self - interstitials (and vacancies) plays a minor role in the preci-pitate formation. On the other hand Cu and Pd precipitate as metal - rich silicide particles. They form star - like colonies consisting of small particles and extended extrinsic edge - type dislocation loops. The precipitation behaviour of these two met-als is governed by the generation of Si - self - interstitials due to the large misfit of the metal - rich silicide particles.