The morphology and growth kinetics of the discontinuous precipitate in a deformed and undeformed Ni-7.5at.%In alloy have been investigated at temperatures ranging from 667?K to?1030?K using light and scanning microsco...The morphology and growth kinetics of the discontinuous precipitate in a deformed and undeformed Ni-7.5at.%In alloy have been investigated at temperatures ranging from 667?K to?1030?K using light and scanning microscopy. Also, the dependence of the growth rate on some diffusion parameters was experimentally and theoretically studied. The investigation is observed that at all aging temperatures the alloy was observed to decompose completely by discontinuous precipitation into a fine lamellar structure of nickel-rich solid solution and?β?(Ni3In) precipitate phase. The precipitation rate depends strongly on the degree of deformation, this dependence being identical for each of the aging temperatures under investigation. Analysis of the growth rates, lamellar spacing and phase compositions for the discontinuous precipitation reaction showed that they were controlled by grain boundary diffusion. Moreover, a generally applicable procedure for calculating the driving force is presented. The driving forces, calculated in this way, should be more reliable than those calculated with the approximations based on Peterman and Hornbogen laws.展开更多
文摘The morphology and growth kinetics of the discontinuous precipitate in a deformed and undeformed Ni-7.5at.%In alloy have been investigated at temperatures ranging from 667?K to?1030?K using light and scanning microscopy. Also, the dependence of the growth rate on some diffusion parameters was experimentally and theoretically studied. The investigation is observed that at all aging temperatures the alloy was observed to decompose completely by discontinuous precipitation into a fine lamellar structure of nickel-rich solid solution and?β?(Ni3In) precipitate phase. The precipitation rate depends strongly on the degree of deformation, this dependence being identical for each of the aging temperatures under investigation. Analysis of the growth rates, lamellar spacing and phase compositions for the discontinuous precipitation reaction showed that they were controlled by grain boundary diffusion. Moreover, a generally applicable procedure for calculating the driving force is presented. The driving forces, calculated in this way, should be more reliable than those calculated with the approximations based on Peterman and Hornbogen laws.
