ISSN:
1573-2738
Keywords:
back stress
;
creep
;
dislocation
;
dispersion
;
grain boundary
;
Norton plot
;
particle hardening
;
reaction-milling
;
threshold stress
;
work hardening
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Dispersion-hardened aluminum materials of pure aluminum with extremely fine oxide and carbide dispersions and very fine grain sizes were creep-deformed under compressive loadings between 573 and 773 K. The creep behavior of the investigated materials is influenced by time, temperature, stress level and microstructure. An increasing content of dispersions causes increasing threshold stresses σthand resistances against creep. The Norton plots of the minimum creep rate $$\dot \varepsilon _{\min } $$ versus stress σ are characterized by extremely high stress exponents n. On the basis of the threshold concept it is demonstrated that the same diffusion process dominates in the dispersion-hardened aluminum materials as in pure aluminum. Their true stress exponents n*as the slopes of the best fit lines of the $$\log \dot \varepsilon _{\min } {\text{ }}versus{\text{ }}\log (\sigma - \sigma _{{\text{th}}} )$$ are close to 5. The threshold stress decreases considerably with increasing temperature due to the thermally activated recovery of long-range internal back stresses of quasi-planar dislocation structures on the grain boundaries.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009875316242
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