UNLOADING EFFECTS IN THE PLASTIC PROPERTIES OF COPPER SINGLE CRYSTALS

Journal Article · Sat Mar 01 04:00:00 EST 1958 · Phil. Mag.

OSTI ID:4344792

Makin, M J

Yield point phenomena occur on retesting copper single crystals during interrupted tensile deformation. The effect is observed only during the linear and parabolic regions of the stress--strain curve and the size of the yield drop is directly proportional to the reduction in stress on unloading. The ratio of the flow stress immediately before complete unloading to that on retesting is 0.986, and appears to be independent of temperature between --195 deg C and 100 deg C. The magnitude of the yield phenomenon at --195 deg C is markedly increased, however, by annealing at above --170 deg C, and this effect is independent of the amount of unloading. An explanation of these phenomena is advanced in which Lomer--Cottrell sessile dislocations are formed during unloading, and that it is these dislocations which prevent large scale reverse plasticity. The increased effect at --195 deg C on annealing is interpreted in terms of the thermally activated reversal of the apices of these sessile dislocations. (auth)

• Research Organization: Atomic Energy Research Establishment, Harwell, Berks, Eng.
• NSA Number: NSA-12-007904
• OSTI ID: 4344792
• Journal Information: Phil. Mag., Journal Name: Phil. Mag. Vol. Vol: (8) 3
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ANNEALING
COPPER
DEFORMATION
DUCTILITY
MONOCRYSTALS
PHYSICS
STRESSES
TEMPERATURE