Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Koizumi, Yuichiro; Suzuki, S.; Yamanaka, Kazushi; Lee, Byoung Soo; Sato, Kazuhisa; Li, Yunping; Kurosu, Shingo; Matsumoto, Hiroaki; Chiba, Akihiko

doi:10.1016/j.actamat.2012.11.041

Cited by 153 publications

(58 citation statements)

References 49 publications

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“…These results suggest that the plastic deformation leads to the FCC to HCP transformation during tensile tests. 25,26) It has been reported that the FCC to HCP transformation occurs relatively easily in the finegrained CoCrMo alloys, and the formation of ¾-HCP phase has an adverse effect on the ductility of the CoCrMo alloys. 27,28) Since harmonic structured CoCrMo alloys consist of fine-grained "shell" regions, the effect of FCC to HCP transformation on the mechanical properties is expected to be very prominent with increasing "shell" volume fraction.…”

Section: Deformation Induced Fcc To Hcp Transformationmentioning

confidence: 99%

Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties

et al. 2014

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Harmonic structure is a recently introduced concept for material microstructure design. It is essentially a bimodal microstructure in which deliberately introduced structural heterogeneity has a specific order: interconnected network of ultra-fine grained (UFG) regions, called "shell area", and coarse-grained regions called "core area". Such microstructural features dictate a unique set of properties to the Harmonic-structured materials. The present paper deals with the application of harmonic structure design to biomedical CoCrMo alloys for improved mechanical properties. In the present work, it has been demonstrated that full density CoCrMo alloy compacts with harmonic structure can be successfully prepared by controlled mechanical milling followed by spark plasma sintering of the pre-alloyed powders at 1323 K for 3.6 ks. Sintered compacts exhibited an excellent combination of strength and ductility. Moreover, it has been also shown that the mechanical properties depend strongly on the volume fraction of the inter-connected three-dimensional network of fine-grained regions, i.e., shell volume fraction. In addition, the plastic deformation of harmonic structure CoCrMo alloy also led to ¡-FCC to ¾-HCP allotropic transformation. Therefore, the application of harmonic structure design leads to the new generation microstructure of biomedical CoCrMo alloys, which demonstrates outstanding mechanical properties compared to conventional materials.

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Section: Deformation Induced Fcc To Hcp Transformationmentioning

confidence: 99%

Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties

et al. 2014

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“…[1][2][3] The mechanical properties of CCM alloys need to be further improved to reduce the probability of failure in biomedical applications. 4) Grain re nement is effective to improve the mechanical properties of CCM alloys. In fact, CCM alloys with small grain size have been practically used.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

et al. 2016

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The main target of this study is to optimize the microstructure and to achieve an optimization for the mechanical properties in a biomedical Co-Cr-Mo (CCM) alloy with the nominal composition of Co-28Cr-6Mo (mass%) subjected to high-pressure torsion (HPT) and subsequent short annealing. The γ → ε phase transformation and grain re nement occur in the CCM alloy subjected to HPT processing at an equivalent strain (ε eq ) of 2.25 (CCM HPT ). The HPT processing causes a decrease in the elongation due to the formation of an excessive amount of ε phase. For removal of the excessive amount of ε phases, the CCM HPT was subjected to a short annealing (CCM HPTA ). The effect of the short annealing temperature (1073 K, 1273 K, and 1473 K; annealing time was xed at 0.3 ks) on CCM HPT was investigated. In addition, the effect of the length of duration for the short annealing (0.06 ks, 0.3 ks, and 0.6 ks;) for a xed annealing temperature of 1273 K on CCM HPT was studied. CCM HPTA(1273 K) annealed for 0.3 ks shows a good optimization of mechanical properties that include high strength and large elongation owing to its ultra ne-grained microstructure, and removal of excessive ε phases.

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“…However, in the magnified BSE image (Figure 6c), thin plate-like structures can be found. According to Koizumi et al, these seem to be twin and/or HCP martensite [16]. It should be noted that this submicron structure is completely neglected in Figure 6a,b, i.e., EBSD measurement.…”

Section: Texturementioning

confidence: 88%

Strain-Induced Martensitic Transformation and Texture Evolution in Cold-Rolled Co–Cr Alloys

Onuki

Sato

Nakagawa

et al. 2018

QuBS

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Co-Cr alloys have been used in biomedical purposes such as stents and artificial hip joints. However, the difficulty of plastic deformation limits the application of the alloys. During the deformation, Co-Cr alloys often exhibit strain-induced martensitic transformation (SIMT), which is a possible reason for the low formability. The distinct increase in dislocation density in the matrix phase may also result in early fractures. Since these microstructural evolutions accompany the textural evolution, it is crucial to understand the relationship among the SIMT, the increase in dislocations, and the texture evolution. To characterize those at the same time, we conducted time-of-flight neutron diffraction experiments at iMATERIA beamline at the Japan Proton Accelerator Research Complex (J-PARC) Materials and Life Science Experimental Facility (MLF), Ibaraki, Japan. The cold-rolled sheets of Co-29Cr-6Mo (CCM) and Co-20Cr-15W-10Ni (CCWN) alloys were investigated in this study. As expected from the different stacking fault energies, the SIMT progressed more rapidly in the CCM alloy. The dislocation densities of the matrix phases of the CCM and CCWN alloys increased similarly with an increase in the rolling reduction. These results suggest that the difference in deformability between the CCM and CCWN alloys originate not from the strain hardening of the matrix phase but from the growth behaviors of the martensitic phase.

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Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Cited by 153 publications

References 49 publications

Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties

Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

Strain-Induced Martensitic Transformation and Texture Evolution in Cold-Rolled Co–Cr Alloys

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Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Cited by 153 publications

References 49 publications

Application of Harmonic Structure Design to Biomedical Co&ndash;Cr&ndash;Mo Alloy for Improved Mechanical Properties

Application of Harmonic Structure Design to Biomedical Co&ndash;Cr&ndash;Mo Alloy for Improved Mechanical Properties

Optimization of Microstructure and Mechanical Properties of Co–Cr–Mo Alloys by High-Pressure Torsion and Subsequent Short Annealing

Strain-Induced Martensitic Transformation and Texture Evolution in Cold-Rolled Co–Cr Alloys

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Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties

Application of Harmonic Structure Design to Biomedical Co–Cr–Mo Alloy for Improved Mechanical Properties