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Silicate glass fracture surface energy calculated from crystal structure and bond-energy data
(2023)
We present a novel method to predict the fracture surface energy, γ, of isochemically crystallizing silicate glasses using readily available crystallographic structure data of their crystalline counterpart and tabled diatomic chemical bond energies, D0. The method assumes that γ equals the fracture surface energy of the most likely cleavage plane of the crystal. Calculated values were in excellent agreement with those calculated from glass density, network connectivity and D0 data in earlier work. This finding demonstrates a remarkable equivalence between crystal cleavage planes and glass fracture surfaces.
The life time of mechanical components in high temperature applications is basically determined by their workings. Corrosion determines the loss of material corresponding to the loss of the effective load-bearing section and consequently increasing stress levels. To improve the material selection for such applications a numerical life prediction corrosion model for different alloys and environments is needed. Based on the ferritic alloys FeCr and FeCrCo a first quantitative model is to be developed. For this purpose, the alloys are aged at 600 °C, 650 °C and 700 °C in synthetic air under normal pressure for between 10 and 240 hours. The first objective is to establish a quantitative relationship between the oxidation rate as a function of composition and microstructure of the alloys. The influence of the inner interface as an essential parameter for transport by diffusion on the oxidation kinetics is discussed in this paper.
The life time of mechanical components in high temperature applications is basically determined by their workings. Corrosion determines the loss of material corresponding to the loss of the effective load-bearing section and consequently increasing stress levels. To improve the material selection for such applications a numerical life prediction corrosion model for different alloys and environments is needed. Based on the ferritic alloys FeCr and FeCrCo a first quantitative model is to be developed. For this purpose, the alloys are aged at 600°C, 650°C and 700°C in synthetic air under normal pressure for between 10 and 240 hours. The first objective is to establish a quantitative relationship between the oxidation rate as a function of composition and microstructure of the alloys. The influence of the inner interface as an essential parameter for transport by diffusion on the oxidation kinetics is discussed in this presentation.
Interdiffusion in the Face-Centered Cubic Phase of the Co-Al-W-Ta System Between 1090 and 1240 °C
(2018)
Interdiffusion of Al, W, Ta and Co in a Co-base alloy at temperatures between 1090 and 1240 °C has been investigated. The interdiffusion coefficients were found to be close to those reported for these elements in Ni-base alloys. Combining the diffusion simulation software DICTRA with the Ni-base diffusion databases TCNi5 and MobNi3, the interdiffusion profiles of Co, Al W, and Ta were modeled for Co9Al8W2Ta/Co diffusion couples annealed at different temperatures and for different times. The results show that interdiffusion in the Co-Al-W-Ta alloys can be modeled reasonably well using the available commercial databases for thermodynamics and kinetics of Ni-base systems.