Helical dislocations in quenched aluminium-4% copper alloys

摘要: Abstract Experiments by transmission electron microscopy on thin foils of polycrystalline A1-4 % Cu alloys, quenched from various temperatures have revealed helical dislocation lines which are thought to be produced condensation vacancies dislocations predominantly screw character. The axes the helices parallel Burgers vector, i.e. [110] directions. In material 500°c and 540°c vary in radius pitch about 250 A more than 1500 A. Materiel 440°c contains irregular with several hundred angstroms much smeller radius. Preliminary estimates suggest that vacancy concentration required produce observed climb is ∼3 × 10−5(500° quenches) ∼ 2 10−6(440°c quench). appear interact each other intertwined rows loops. Observations connected opposite hand lengths dislocat...