TY - JOUR
T1 - Anomalous hardening and microstructural evolution accompanied by reordering and restoring of plastically deformed Co3Ti
AU - Oka, Takahiro
AU - Kaneno, Yasuyuki
AU - Semboshi, Satoshi
AU - Nakamura, Ryusuke
AU - Takasugi, Takayuki
N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS).
Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2015/1/3
Y1 - 2015/1/3
N2 - The anomalous hardening and microstructural evolution accompanied by the reordering and restoring of cold-rolled Co3Ti alloy annealed at 573-773K were investigated by hardness testing, SEM and TEM observations, XRD analysis and DSC measurements. The hardening observed in the heavily cold-rolled samples was similar to that observed in precipitation reactions, with the hardness increasing with increasing annealing time to a point and then decreasing. The hardness peak occurred more rapidly at higher annealing temperatures, and the annealing time leading to this peak was insensitive to the degree of cold-rolling reduction. The stored lattice strain evaluated from the half-width of the X-ray reflection peak steadily decreased with increasing annealing time but remained relatively high regardless of the degree of cold-rolling reduction or annealing temperature. The TEM deformation microstructures showed that a high density of dislocations was attained, even in an over-aged state. DSC measurements showed two exothermic peaks at low and high temperatures, which were attributed to the annihilation of point defects and/or reordering and to the rearrangement of dislocations, respectively. The observed anomalous hardening was discussed in association with the reordering of the mechanically disordered structure and the restoring of the plastically deformed microstructure.
AB - The anomalous hardening and microstructural evolution accompanied by the reordering and restoring of cold-rolled Co3Ti alloy annealed at 573-773K were investigated by hardness testing, SEM and TEM observations, XRD analysis and DSC measurements. The hardening observed in the heavily cold-rolled samples was similar to that observed in precipitation reactions, with the hardness increasing with increasing annealing time to a point and then decreasing. The hardness peak occurred more rapidly at higher annealing temperatures, and the annealing time leading to this peak was insensitive to the degree of cold-rolling reduction. The stored lattice strain evaluated from the half-width of the X-ray reflection peak steadily decreased with increasing annealing time but remained relatively high regardless of the degree of cold-rolling reduction or annealing temperature. The TEM deformation microstructures showed that a high density of dislocations was attained, even in an over-aged state. DSC measurements showed two exothermic peaks at low and high temperatures, which were attributed to the annihilation of point defects and/or reordering and to the rearrangement of dislocations, respectively. The observed anomalous hardening was discussed in association with the reordering of the mechanically disordered structure and the restoring of the plastically deformed microstructure.
KW - Age hardening
KW - CoTi
KW - Ordering
KW - Recovery
KW - Restoring
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U2 - 10.1016/j.msea.2014.10.035
DO - 10.1016/j.msea.2014.10.035
M3 - Article
AN - SCOPUS:84910101387
VL - 620
SP - 411
EP - 419
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
SN - 0921-5093
ER -