Strain Age Hardening of Aluminium Alloys

概要

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The strain age hardening of Al-Cu, Al-Mg and Al-Si alloys was studied and the results obtained were as follows : (1) The characteristics of hardening are generally similar to those of carbon steels, copper alloys and austenitic steels, although its degree is appreciably low. (2) In Al-4.9 per cent Cu alloy solution-treated and aged, the strain age hardening and the inelastic effect are less marked in a fully age-hardened state than in an over-aged state, the difference being probably due to the circumstances that dislocations pass through GP zones, whereas the θ' and θ phases act as an effective barrier against dislocation movement, pile-ups of dislocation being formed in a large number. (3) The hardening is generally marked in such an alloy as exhibiting high degrees of work hardening rate and X-ray line broadening, these being relatively low in aluminium alloys. The effect of alloying on the strain age hardening seems to form strong barriers against the movement of dislocations and a high density of piled-up dislocations during cold working rather than to take short range ordering or to segregate into stacking faults during low temperature annealing.