Dataset Information

Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy.

ABSTRACT: To elucidate the hot deformation characteristics of TiAl alloys, flow stress prediction, microstructural evolution and deformation mechanisms were investigated in Ti-44Al-5Nb-1Mo-2V-0.2B alloy by isothermal compression tests. A constitutive relationship using the Arrhenius model involving strain compensation and back propagation artificial neural network (BP-ANN) model were developed. A comparison of two models suggested that the BP-ANN model had excellent capabilities and was more accurate in predicting flow stress. Based on the microstructural analysis, bending and elongation of colonies, ? and B2 grains were the main microstructural constituents at low temperature and high strain rate. Dynamic recrystallization (DRX) of ? and dynamic recovery (DRY) of ?/B2 were the main deformation mechanisms. With the increase of temperature and decrease of strain rate, phase transformation played an important role. The flake-like ? precipitates in B2 grains, and a coarsening of ? lamellae via ? lath dissolution during compression were observed. Additionally, the flow softening process commenced with dislocation pile-up and formation of sub-grain boundaries, followed by grain refinement, twins and nano-lamellar nucleation. Continuous DRX and phase transformation promoted the formability of Ti-44Al-5Nb-1Mo-2V-0.2B alloy.

SUBMITTER: Li T

PROVIDER: S-EPMC6213516 | biostudies-other | 2018 Oct

REPOSITORIES: biostudies-other

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Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy.

Li Tianrui T Liu Guohuai G Xu Mang M Wang Bingxing B Fu Tianlian T Wang Zhaodong Z Misra Raja Devesh Kumar RDK

Materials (Basel, Switzerland) 20181019 10

To elucidate the hot deformation characteristics of TiAl alloys, flow stress prediction, microstructural evolution and deformation mechanisms were investigated in Ti-44Al-5Nb-1Mo-2V-0.2B alloy by isothermal compression tests. A constitutive relationship using the Arrhenius model involving strain compensation and back propagation artificial neural network (BP-ANN) model were developed. A comparison of two models suggested that the BP-ANN model had excellent capabilities and was more accurate in p ...[more]

PMID: 30347775

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Project description:Highlights • Ti-8Mo-2Fe was resistant to pitting corrosion in PBS, a clear advantage over 316 L.• Ti-8Mo-2Fe exhibited similar corrosion rate in PBS than pure ti and 316 L.• Ti-8Mo-2Fe alloy did not generate acute hemolysis.• Blood coagulation was retarded on ti-8mo-2fe surface in comparison to pure Ti.• The proliferation rate of ECs and SMCs on ti-8mo-2fe was lower than on 316 L. There is a deep interest in developing new Ni-free Ti-based alloys to replace 316 L stainless steel and Co-Cr alloys for endovascular stent application, mainly because the release of Ni can generate toxicity and allergenicity. Interactions of Ti alloy biomaterials with bone cells and tissues have been widely investigated and reported, while interactions with vascular cells and tissues, such as endothelial cells (ECs) and smooth muscle cells (SMCs), are scarce. Therefore, this study focused on the relationship among the surface finishing features, corrosion behavior and in vitro biological performances regarding human ECs, SMCs and blood of a newly developed Ti-8Mo-2Fe (TMF) alloy, specifically designed for balloon-expandable stent applications. The alloy performances were compared to those of 316 L and pure Ti, prepared with the same surface finishing techniques, which are mechanical polishing and electropolishing. Surface properties were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA) and x-ray photoelectron spectroscopy (XPS). The corrosion behavior was assessed with potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests in phosphate buffered saline (PBS) solution. No significant differences were observed regarding the corrosion rate measured with PDP analyses, which was of the order of 2 × 10−4 mm/y for all the studied materials. Moreover, similarly to pure Ti, TMF exhibited an advantage over 316 L for biomedical applications, namely remarkable resistance to pitting corrosion up to high potentials. The results evidenced a good cytocompatibility and hemocompatibility, making this group of alloy a potential candidate for cardiovascular implants. In fact, both ECs and SMCs proliferated on TMF surfaces showing a 7-day viability similar to that of pure Ti. Regarding hemocompatibility, TMF did not cause hemolysis, and blood coagulation was delayed on its surface in comparison to pure Ti. When compared to 316 L, TMF showed similar hemocompatibility.

Dataset Information

Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy.

Publications

Flow Stress Prediction and Hot Deformation Mechanisms in Ti-44Al-5Nb-(Mo, V, B) Alloy.

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