| A detailed analysis has been made of the creep relation, ε˙_s=A(σ-σ_ο)⁴exp(-ΔH/kT), in dispersion strengthened alloys where Wilshire and co-workers have directly measured the friction or internal stress, σ_ο. Values of a normalized friction stress σ_ο and a applied stress σ are shown to fit a simple empirical relation very well. The stress exponents calculated from the relation when compared with actual values reveal new features in the experimental creep data, such as variation in the constant, A, due to microstructural change. Another interesting feature in this analysis is that stress exponents comparable with those in dispersion strengthened nickel (∼60) may be obtained by suitable choice of parameters. |
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