The effect of boron on the refinement of microstructure in cast cobalt alloys

Bermingham, Michael; McDonald, Stuart D.; StJohn, David H.; Dargusch, Matthew S.

doi:10.1557/jmr.2011.21

Cited by 19 publications

(5 citation statements)

References 28 publications

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“…A possible boron-carbon network of Co x -B x , Cr x -B x , Mo x -B x , and B x C x could be identified for the B2 and B3 samples. According to previous authors [19,[25][26][27], carbon could be partially substituted by boron, resulting in the formation of different compounds. In addition, this network exhibited a preferential alienation into interdendritic and grain boundaries (B3 sample).…”

Section: Discussionmentioning

confidence: 93%

In Vitro Biocompatibility Evaluation of a New Co-Cr-B Alloy with Potential Biomedical Application

Garcia-Mendez

Urrutia-Baca

Cuao-Moreu

et al. 2021

Metals

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Cobalt–chromium (Co-Cr) alloys have been used in a wide variety of biomedical applications, including dental, cardiovascular, and orthopedic devices. In vitro studies have shown that the mineralization of cells involved in osteogenesis is regulated by boron. The development of a new cobalt-chromium-boron (Co-Cr-B) alloy improves the mechanical properties of the metal, such as wear resistance, and meets biocompatibility requirements. Therefore, the objective of this study was to evaluate the osteogenic differentiation and biocompatibility in in vitro assays. Human dental pulp mesenchymal cells (hDPSCs) were isolated from volunteers and then co-cultured with the Co-Cr plus boron alloy from 0.3% to 1% for 15 days, while the formation of calcium deposits was quantified by Alizarin red staining and the expression of genes was related to osteodifferentiation by RT-qPCR. Simultaneously, the cytotoxicity of our alloy was evaluated by MTT assay and the change in the gene expression of cytokines commonly associated with inflammatory processes. The results showed low cytotoxicity when cells were treated with the Co-Cr-B alloy, and no change in the gene expression of IL-1β, TNF-α, IL-6, and IL-8 was observed compared to the untreated control (p > 0.05). The osteoinduction results shown an increase in mineralization in hDPSCs treated with Co-Cr-B alloy with 1.0% B. In addition, a significant increase in mRNA levels for collagen type 1 in with 0.3% boron and alkaline phosphatase and Runx2 with 0.6% boron were observed. The addition of Boron to the ASTM F75 Co-Cr base alloy improves the biocompatible characteristics. No cytotoxicity and any change of the expression of the pro-inflammatory cytokines IL-1β, TNF-α, IL-6, and IL-8 in human peripheral blood mononuclear cells treated with the cobalt-chromium-boron alloy was observed in vitro assays. Furthermore, our alloy acts as an osteoinductive in osteogenic differentiation in vitro. Therefore, our results could set the standard for the development of in vivo trials and in the future, it could be considered as an alternative for regenerative therapy.

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Section: Discussionmentioning

confidence: 93%

In Vitro Biocompatibility Evaluation of a New Co-Cr-B Alloy with Potential Biomedical Application

Garcia-Mendez

Urrutia-Baca

Cuao-Moreu

et al. 2021

Metals

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“…However, the strength of as-sintered titanium is higher than that of ASM standard CP titanium (grade 4). This is attributed to the α laths in the as-sintered microstructure of the titanium , which contribute to higher strength compared with the equiaxed grained microstructure typical of as-cast titanium ingots [6,7]. After extruding at 900ºC in air, the mechanical properties of CP titanium were significantly improved compared with as-sintered titanium, with a UTS of 705MPa, YS of 650MPa…”

Section: Resultsmentioning

confidence: 99%

High Strength Titanium Rods Produced by Thermomechanical Powder Consolidation

Yang

Gabbitas

Singh

et al. 2016

MSF

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In this paper, pure titanium rods, with high strength and ductility, were prepared by vacuum sintering titanium powder compacts at 1300oC for 2h and then hot extruding the as-sintered titanium billets at 900oC in air. The microstructure and property changes, after vacuum sintering and hot extrusion, were investigated. The results showed clear evidence of porosity in the microstructure of as-sintered titanium billet and tensile testing of as-sintered material gave yield strength, ultimate tensile strength and ductility values of 570MPa, 602MPa and 4%, respectively. After extrusion at 900oC, no obvious pores could be seen in the microstructure of as-extruded titanium rod, and the mechanical properties were significantly improved. The yield strength, ultimate tensile strength and the ductility reached 650MPa, 705MPa and 20%, respectively, which are much higher than values for CP titanium (grade 4), with a yield strength of 480MPa, ultimate tensile strength of 550MPa and ductility of 15%. The fracture characteristics of as-sintered and as-extruded titanium rods have also been investigated.

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“…Solute is rejected laterally as well as in the build-direction. Lateral build-up of solute restricts growth causing the formation of thinner columnar grains [11,12]. Fig.…”

Section: Formation Of Equiaxed Grains During Ammentioning

confidence: 99%

The Challenges Associated with the Formation of Equiaxed Grains during Additive Manufacturing of Titanium Alloys

John

McDonald

Bermingham

et al. 2018

KEM

Self Cite

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It is well established that columnar grain structures usually form when metal alloys are used to additively manufacture components. A challenging goal is to produce an equiaxed grain structure throughout the component to remove anisotropy and refine the grain size in order to improve its mechanical performance. The high cooling rates and associated high temperature gradients are the main reasons for the formation of columnar grains via epitaxial growth of each added layer of material. There appear to be limited strategies for promoting equiaxed nucleation of grains. In addition to cooling rate and temperature gradient, we explore other variables such as the potency of natural or added inoculant particles and the composition of the alloy, and their possible impact on the nucleation of equiaxed grains. Although changing the composition can help, finding a suitably potent nucleant particle is a major challenge. Operating parameters can also influence the microstructure and optimization to produce equiaxed grains may be possible. The limitations of these strategies and possible ways to overcome them are evaluated.

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The effect of boron on the refinement of microstructure in cast cobalt alloys

Cited by 19 publications

References 28 publications

In Vitro Biocompatibility Evaluation of a New Co-Cr-B Alloy with Potential Biomedical Application

In Vitro Biocompatibility Evaluation of a New Co-Cr-B Alloy with Potential Biomedical Application

High Strength Titanium Rods Produced by Thermomechanical Powder Consolidation

The Challenges Associated with the Formation of Equiaxed Grains during Additive Manufacturing of Titanium Alloys

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