A study of the interactive effects of strain, strain rate and temperature in severe plastic deformation of copper

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

“…[6] High speed and low temperature (over~33 of ln Z) are required for twinning to be activated as one of the main deformation mechanisms in copper, and the twin fraction increases with increasing ln Z. [7,8] Thus, the CTD sample with~64 of ln Z could have many twin boundaries. However, the whole microstructure was not covered by twins due to the limitation of the volume fraction of the deformation twins.…”

“…To understand the effect of the Z parameter at not only extreme but also ordinary conditions, the deformation of copper over a wide range of temperature and strain rate were studied. [6][7][8] However, these studies have three deficiencies: (1) few study at strain rates over~10 3 s À1 and at cryogenic temperature, (2) less consideration for global microstructural features than for local microstructural ones, and (3) insufficient attention to reheating from cryogenic temperature to room temperature after the deformation.…”

“…In order to further decrease the lower bound of the grain size, and to expand the microstructural window of SPD-processed materials, many researchers have been interested in controlling processing parameters, such as strain rate and temperature, at extreme levels. [6][7][8][9][10] The simultaneous effects of strain rate and temperature on microstructural evolution during plastic deformation are generally expressed by the Zener-Hollomon parameter, Z, as follows:…”

Enhancing surface integrity by high-speed extrusion machining

“…Actually, for low-speed machining (LSM), Chiffre put forward extrusion cutting to impose the extrusion stress in PSZ for controlling the chip formation process [26]. Chandrasekar and co-workers further devised a large-strain extrusion machining (LSEM) apparatus to fabricate ultrafine grain materials (UFGs) at a low cutting speed [27]. Recently, inspired by the works of Chiffre and Chandrasekar, Dai et al developed a high-speed extrusion machining (HSEM) device to research the effect of constraint on the chip formation during HSM [28].…”

Vacancies, twins, and the thermal stability of ultrafine-grained copper

“…A dense nano-scale network of twins can be introduced using high-rate, pulsed deposition [1][2][3] or severe plastic deformation (SPD). [4][5][6] Interest in nano-twinned microstructures stems from the finding that twin interfaces support pile-ups and yet provide for dislocation accommodation, thereby enhancing strength and ductility simultaneously. 2,7 Twinned microstructures also have demonstrated enhanced electrical performance, fracture toughness, and stability against cyclic loading.…”