In order to clarify the combined effect of solution and dispersion hardening at high temperatures, the internal stress, effective stress and dislocation density in Al-3 at% Mg-1 at% Mn alloy have been measured and compared with those in Al-3 at% Mg alloy. The measurement has been carried out by applying the stress relaxation technique to the steady state tensile deformation at temperatures from 573 to 723 K and strain rates from 3 × 10-5 to 3 × 10-3 s-1. The additive rule of hardening by solute Mg atoms and dispersed Al6Mn particles holds in the low Z region, but the effect of dispersion hardening decreases with the increase in Z, where Z is the Zener-Hollomon parameter. This behavior is explained by the relative value of the inter-dislocation spacing to the inter-dispersoid spacing. In the low Z region where the dislocation spacing is larger than the dispersoid spacing, nearly all dislocations undergo the resistance of dispersoids, and the additive rule holds. In the high Z region, the dislocation spacing becomes smaller than the dispersoid spacing, and the part of dislocations not directly contacting the dispersoids increases as Z increases, resulting in the decrease of the effect of dispersion hardening.
|Number of pages||11|
|Journal||Transactions of the Japan Institute of Metals|
|Publication status||Published - Jan 1 1990|
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