Thermal behavior of copper processed by ECAP with and without back pressure

TY - JOUR

T1 - Thermal behavior of copper processed by ECAP with and without back pressure

AU - Wang, Ya Li

AU - Lapovok, Rimma

AU - Wang, Jing Tao

AU - Qi, Yuan Shen

AU - Estrin, Yuri

N1 - Publisher Copyright: © 2015 Elsevier B.V.

PY - 2015/3/5

Y1 - 2015/3/5

N2 - Samples of electrolytic tough pitch (ETP) pure copper were subjected to 12 passes of Equal-Channel Angular Pressing (ECAP) at room temperature with and without back pressure. Subsequent annealing was performed to evaluate the influence of back pressure during ECAP on the thermal behavior of ultrafine-grained copper. The microstructural and hardness changes caused by annealing were characterized by orientation imaging microscopy (OIM) and microhardness measurements. The application of back pressure resulted in an earlier drop in hardness upon annealing, which is believed to be associated with a lower critical temperature for the initiation of recrystallization and a rapid coarsening of microstructure. Regardless of whether back pressure was applied or not, structure coarsening during short-time annealing of ECAP-processed copper was governed by discontinuous static recrystallization. This is seen as a result of microstructure heterogeneity. Analysis of recrystallization kinetics was carried out based on observations of the microstructure after annealing in terms of the Avrami equation. The magnitude of the apparent activation energies for recrystallization in the absence of back pressure and in the case of back pressure of 100. MPa was estimated to be ~99. kJ/mol and ~91. kJ/mol, respectively. The reasons for reduced activation energy in the case of processing with back pressure are discussed.

AB - Samples of electrolytic tough pitch (ETP) pure copper were subjected to 12 passes of Equal-Channel Angular Pressing (ECAP) at room temperature with and without back pressure. Subsequent annealing was performed to evaluate the influence of back pressure during ECAP on the thermal behavior of ultrafine-grained copper. The microstructural and hardness changes caused by annealing were characterized by orientation imaging microscopy (OIM) and microhardness measurements. The application of back pressure resulted in an earlier drop in hardness upon annealing, which is believed to be associated with a lower critical temperature for the initiation of recrystallization and a rapid coarsening of microstructure. Regardless of whether back pressure was applied or not, structure coarsening during short-time annealing of ECAP-processed copper was governed by discontinuous static recrystallization. This is seen as a result of microstructure heterogeneity. Analysis of recrystallization kinetics was carried out based on observations of the microstructure after annealing in terms of the Avrami equation. The magnitude of the apparent activation energies for recrystallization in the absence of back pressure and in the case of back pressure of 100. MPa was estimated to be ~99. kJ/mol and ~91. kJ/mol, respectively. The reasons for reduced activation energy in the case of processing with back pressure are discussed.

KW - Back pressure

KW - Copper

KW - Equal Channel Angular Pressing (ECAP)

KW - Recrystallization

KW - Thermal stability

UR - http://www.scopus.com/inward/record.url?scp=84922162266&partnerID=8YFLogxK

U2 - 10.1016/j.msea.2015.01.021

DO - 10.1016/j.msea.2015.01.021

M3 - 文章

AN - SCOPUS:84922162266

SN - 0921-5093

VL - 628

SP - 21

EP - 29

JO - Materials Science and Engineering: A

JF - Materials Science and Engineering: A

ER -