TY - JOUR
T1 - Microstructural effects and large microhardness in cobalt processed by high pressure torsion consolidation of ball milled powders
AU - Sort, J.
AU - Zhilyaev, A.
AU - Zielinska, M.
AU - Nogués, J.
AU - Suriñach, S.
AU - Thibault, J.
AU - Baró, M. D.
PY - 2003/12/8
Y1 - 2003/12/8
N2 - The effects of plastic deformation on Co microstructure after a high pressure torsion (HPT) process on unmilled and ball milled powders have been studied and compared to those induced simply by ball milling (BM). X-ray diffraction analyses reveal that both processing routes generate large amounts of stacking faults in Co, which result in a mixture of hcp and fcc phases. However, significant differences in the amount and type of faults accumulated are encountered between BM and HPT. The combination of both processing routes induces a heavily distorted microstructure in Co. In particular, BM + HPT brings about a drastic reduction in crystallite size. Remarkably, high values of microhardness (in excess of HV = 7.3 GPa) are obtained in foils prepared by long-term milling followed by HPT. It is proposed that, in addition to the crystallite size refinement, the large amounts of twin faults, together with the two-phase mixture, also contribute to enhance the microhardness. © 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
AB - The effects of plastic deformation on Co microstructure after a high pressure torsion (HPT) process on unmilled and ball milled powders have been studied and compared to those induced simply by ball milling (BM). X-ray diffraction analyses reveal that both processing routes generate large amounts of stacking faults in Co, which result in a mixture of hcp and fcc phases. However, significant differences in the amount and type of faults accumulated are encountered between BM and HPT. The combination of both processing routes induces a heavily distorted microstructure in Co. In particular, BM + HPT brings about a drastic reduction in crystallite size. Remarkably, high values of microhardness (in excess of HV = 7.3 GPa) are obtained in foils prepared by long-term milling followed by HPT. It is proposed that, in addition to the crystallite size refinement, the large amounts of twin faults, together with the two-phase mixture, also contribute to enhance the microhardness. © 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
KW - Mechanical milling
KW - Microhardness
KW - Phase transformations
KW - Severe plastic deformation
KW - Twinning
U2 - https://doi.org/10.1016/j.actamat.2003.08.006
DO - https://doi.org/10.1016/j.actamat.2003.08.006
M3 - Article
VL - 51
SP - 6385
EP - 6393
ER -