Comparative Study of Oswald Ripening and Trans-Interface Diffusion-Controlled Theory Models: Coarsening of γ " Precipitates Affected by Elastic Strain Along a Concentration Gradient

Comparative Study of Oswald Ripening and Trans-Interface Diffusion-Controlled Theory Models: Coarsening of γ " Precipitates Affected by Elastic Strain Along a Concentration Gradient

According to Lifshitz, Slyozov, and Wagner (LSW) and Trans-Interface Diffusion-Controlled (TICD) theoreticalmodels, this paper reports the microstructure and its coarsening behavior of γ" metastable-coherentprecipitates in concentration gradient of Ni-13.75Ti (at%)/Ni generated by diffusion couple. The coarseningof precipitates was evaluated in two different Ti contents (R1-11.4Ti (at%) and R2-13Ti (at%)) generated alongthe concentration gradient and includes average size, size distributions and growth rate. The solvus andmetastable-coherent bimodal lines as determined at 850 °C of 9.16 (at%) and 9.92Ti (at%) respectively byscanning electron microscopy. This paper suggests that elastic strains produced by the matrix/precipitate latticemismatch caused significant deviations between the experimental results and those predicted by the LSW or TIDCtheories. Activation energies for TIDC (Qi) and LSW (Qr) are Qr: 219.69 and 172.61 kJ mol-1for R1 and R2regions, respectively, and Qi: 218.46 and 164.56 kJmol-1for R1 and R2 regions, respectively. A concentration gradientallows the study of various alloys with different concentration and volume-fraction in a single sample.

According to Lifshitz, Slyozov, and Wagner (LSW) and Trans-Interface Diffusion-Controlled (TICD) theoreticalmodels, this paper reports the microstructure and its coarsening behavior of γ" metastable-coherentprecipitates in concentration gradient of Ni-13.75Ti (at%)/Ni generated by diffusion couple. The coarseningof precipitates was evaluated in two different Ti contents (R1-11.4Ti (at%) and R2-13Ti (at%)) generated alongthe concentration gradient and includes average size, size distributions and growth rate. The solvus andmetastable-coherent bimodal lines as determined at 850 °C of 9.16 (at%) and 9.92Ti (at%) respectively byscanning electron microscopy. This paper suggests that elastic strains produced by the matrix/precipitate latticemismatch caused significant deviations between the experimental results and those predicted by the LSW or TIDCtheories. Activation energies for TIDC (Qi) and LSW (Qr) are Qr: 219.69 and 172.61 kJ mol-1for R1 and R2regions, respectively, and Qi: 218.46 and 164.56 kJmol-1for R1 and R2 regions, respectively. A concentration gradientallows the study of various alloys with different concentration and volume-fraction in a single sample.