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Based on various deformation mechanisms occurring during solid state sintering (pressureless and pressure assisted), a multitude of sintering models have been developed and presented in literature. As reported in literature, most of the simulation results line up well with experimental data. Unfortunately, none of them can be used arbitrarily and none of them are applicable to a generalized case. This paper focuses on a comparative study of three commonly applied models. The first model is based on a physical approach (Riedel) and the other two are phenomenologically based models (the modified SkorohodOlevsky Viscous Sintering (SOVS) model and a modified Abouaf model). The material models have been implemented through FORTRAN Subroutines used for the FE-Software ABAQUS. The simulation results demonstrate their advantages and disadvantages based on sintering simulations of an aluminum oxide based ceramic cylinder and a bilayer laminate. A guideline to select a suitable model and the adjustment of input parameters under different sintering conditions for general usage is also discussed.

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The creep strength of single-crystalline Co-based superalloys was found to be comparable to first-generation Ni-base superalloys. However, considerable shearing of the c¢ precipitates was observed in the early creep stages. To determine the strengthening contribution of the Ta-containing c¢-Co 3 (Al,W) precipitates, the creep strength of several single-crystalline CoAl -W-Ta superalloys was determined as a function of the c¢ volume fraction at 1223 K (950°C) and stress levels between 25 and 600 MPa. Employing a Lagneborg-Bergman-Reppich (LBR) approach, it is found that the strengthening contribution of the c¢ precipitates increases significantly with increasing c¢ volume fraction. In a Co-base superalloy that exhibits a precipitate volume fraction of about 70 pct, the c¢-strengthening contribution calculated with the LBR approach ranges between the ones observed in first-generation Ni-base superalloy CMSX-6 and second-generation Ni-base superalloy CMSX-4.

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