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Local strain evolution due to athermal γ→ε martensitic transformation in biomedical CoCrMo alloys.
J Mech Behav Biomed Mater. 2014 Apr; 32:52-61.JM

Abstract

Locally developed strains caused by athermal γ face-centered cubic (fcc)→ε hexagonal close-packed (hcp) martensitic transformation were investigated for the γ matrix of Ni-free Co-29Cr-6Mo (wt%) alloys prepared with or without added nitrogen. Electron-backscatter-diffraction-(EBSD)-based strain analysis revealed that in addition to ε-martensite interiors, the N-free alloy that had a duplex microstructure consisting of the γ matrix and athermal ε-martensite plates showed larger magnitudes of both elastic and plastic strains in the γ phase matrix than the N-doped counterpart that did not have a ε-martensite phase. Transmission electron microscopy (TEM) results indicated that the ε-martensite microplates were aggregates of thin ε-layers, which were formed by three different {111}γ〈112¯〉γ Shockley partial dislocations in accordance with a previously proposed mechanism (Putaux and Chevalier, 1996) that canceled the shear strains of the individual variants. The plastic strains are believed to have originated from the martensitic transformation itself, and the activity of dislocations is believed to be the origin of the transformation. We have revealed that the elastic strains in the γ matrix originate from interactions among the ε-martensite phase, extended dislocations, and/or thin ε-layers. The dislocations highly dissociated into stacking faults, making stress relaxation at intersections difficult and further introducing local strain evolution.

Authors+Show Affiliations

Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan. Electronic address: k_yamanaka@imr.tohoku.ac.jp.Department of Materials and Environmental Engineering, Sendai National College of Technology, 48 Nodayama, Medeshima-Shiote, Natori 981-1239, Japan.Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

24412717

Citation

Yamanaka, Kenta, et al. "Local Strain Evolution Due to Athermal Γ→ε Martensitic Transformation in Biomedical CoCrMo Alloys." Journal of the Mechanical Behavior of Biomedical Materials, vol. 32, 2014, pp. 52-61.
Yamanaka K, Mori M, Koizumi Y, et al. Local strain evolution due to athermal γ→ε martensitic transformation in biomedical CoCrMo alloys. J Mech Behav Biomed Mater. 2014;32:52-61.
Yamanaka, K., Mori, M., Koizumi, Y., & Chiba, A. (2014). Local strain evolution due to athermal γ→ε martensitic transformation in biomedical CoCrMo alloys. Journal of the Mechanical Behavior of Biomedical Materials, 32, 52-61. https://doi.org/10.1016/j.jmbbm.2013.12.019
Yamanaka K, et al. Local Strain Evolution Due to Athermal Γ→ε Martensitic Transformation in Biomedical CoCrMo Alloys. J Mech Behav Biomed Mater. 2014;32:52-61. PubMed PMID: 24412717.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Local strain evolution due to athermal γ→ε martensitic transformation in biomedical CoCrMo alloys. AU - Yamanaka,Kenta, AU - Mori,Manami, AU - Koizumi,Yuichiro, AU - Chiba,Akihiko, Y1 - 2013/12/24/ PY - 2013/09/29/received PY - 2013/12/04/revised PY - 2013/12/16/accepted PY - 2014/1/14/entrez PY - 2014/1/15/pubmed PY - 2014/10/23/medline KW - Biomedical CoCrMo alloys KW - Electron backscatter diffraction (EBSD) KW - Local strain distribution KW - Martensitic transformation KW - Transmission electron microscopy (TEM) SP - 52 EP - 61 JF - Journal of the mechanical behavior of biomedical materials JO - J Mech Behav Biomed Mater VL - 32 N2 - Locally developed strains caused by athermal γ face-centered cubic (fcc)→ε hexagonal close-packed (hcp) martensitic transformation were investigated for the γ matrix of Ni-free Co-29Cr-6Mo (wt%) alloys prepared with or without added nitrogen. Electron-backscatter-diffraction-(EBSD)-based strain analysis revealed that in addition to ε-martensite interiors, the N-free alloy that had a duplex microstructure consisting of the γ matrix and athermal ε-martensite plates showed larger magnitudes of both elastic and plastic strains in the γ phase matrix than the N-doped counterpart that did not have a ε-martensite phase. Transmission electron microscopy (TEM) results indicated that the ε-martensite microplates were aggregates of thin ε-layers, which were formed by three different {111}γ〈112¯〉γ Shockley partial dislocations in accordance with a previously proposed mechanism (Putaux and Chevalier, 1996) that canceled the shear strains of the individual variants. The plastic strains are believed to have originated from the martensitic transformation itself, and the activity of dislocations is believed to be the origin of the transformation. We have revealed that the elastic strains in the γ matrix originate from interactions among the ε-martensite phase, extended dislocations, and/or thin ε-layers. The dislocations highly dissociated into stacking faults, making stress relaxation at intersections difficult and further introducing local strain evolution. SN - 1878-0180 UR - https://www.unboundmedicine.com/medline/citation/24412717/Local_strain_evolution_due_to_athermal_γ→ε_martensitic_transformation_in_biomedical_CoCrMo_alloys_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1751-6161(13)00430-X DB - PRIME DP - Unbound Medicine ER -