Diffusion-induced bending of Cu-Ni thin sheet diffusion couples

Analysis of Concentration Dependence of Interdiffusion Coefficient under the Condition of a Time-Varying Surface Concentration

“…Significant DIS principally results from compositional gradients in diffusion systems, 16) and is present in systems such as the CuNi system with comparable molar volumes. 15) Several studies by different researchers have experimentally proven the concept of DIS, 14,18,22,23) and importantly, DIS has been experimentally observed in the CuNi system, which is studied in this work. 22) Furthermore, it has been suggested in the literature that an indiscriminate use of diffusion coefficient obtained by traditional methods without due consideration of the influence of DIS on the diffusivity can lead to errors.…”

“…15) Several studies by different researchers have experimentally proven the concept of DIS, 14,18,22,23) and importantly, DIS has been experimentally observed in the CuNi system, which is studied in this work. 22) Furthermore, it has been suggested in the literature that an indiscriminate use of diffusion coefficient obtained by traditional methods without due consideration of the influence of DIS on the diffusivity can lead to errors. 24) Moreover, another careful theoretical analysis of DIS has shown that the effect of the phenomenon tends to be more pronounced under the condition of a timevarying surface concentration compared to when all surface concentrations do not change with time.…”

Change in Concentration-Dependent Diffusion Activation Energy and Frequency Factor with Time: Identified by Numerical Analyses of Experimental Data

“…Accordingly, although it is not commonly considered in the literature, it is conceivable that the concentration dependence of diffusivity, D = F(C), could change with interdiffusion time. Several works by different researchers have experimentally proven the concept of diffusion-induced stress/ strain [21,25,28,29] and D = F(C) indeed changed with time during the interdiffusion process. [29] Furthermore, Belova et al, [9] in their work on the analysis of non-equilibrium concentration of vacancies during interdiffusion, indicates that their theoretical analysis and reported experimental data in the literature show that interdiffusion coefficient can change with time, even though this behavior is often ignored in the literature.…”

“…Several works by different researchers have experimentally proven the concept of diffusion-induced stress/ strain [21,25,28,29] and D = F(C) indeed changed with time during the interdiffusion process. [29] Furthermore, Belova et al, [9] in their work on the analysis of non-equilibrium concentration of vacancies during interdiffusion, indicates that their theoretical analysis and reported experimental data in the literature show that interdiffusion coefficient can change with time, even though this behavior is often ignored in the literature. Therefore, considering that both the generation and relaxation of stress/strain are possible during interdiffusion, [23,30,31] diffusion-induced stress/strain concept could explain both the increase and decrease in concentration-averaged interdiffusion coefficient with time during isothermal diffusion process, as observed in the present work and reported data in the literature.…”

Bending of a Bimetallic Beam Due to the Kirkendall Effect

“…Experiments and models elucidating bending have been executed for solid solution alloys of Au-Ag by Stevens and Powell, [1] of Cu-Ni by Daruka et al, [2] and of Zr-Ti by Opposis et al [3] Suo et al [4] describes a practical application of this subject where the stresses and bending due to the difference of diffusion rates of oxygen and metals in thermal barrier coatings have been investigated. A beam that undergoes transverse diffusion may also bend if the lattice parameter (or alternately, the molar volume) depends on mole fraction even if the intrinsic diffusion coefficients are equal.…”