While ω precipitates in metastable β titanium alloys are typically considered embrittling and consequently deleterious to the mechanical properties, this paper demonstrates that low-temperature aging (LTA) treatments for short time periods can in fact enhance the yield strength while preserving substantial elongation-to-failure in ω containing β titanium alloys. LTA treatments, carried out on a ductile β metastable Ti–12Mo alloy, significantly improve the yield strength of the material (∼55% increase as compared to solution-treated samples) while keeping both TRIP/TWIP effects and a large elongation-to-failure (ϵ = 0.4 in true strain), resulting in a balance of mechanical properties. IMPACT STATEMENT Employing a novel low-temperature annealing strategy, omega precipitates, typically considered embrittling in beta titanium alloys, can effectively increase the yield strength by 50% while preserving 40% tensile ductility. GRAPHICAL ABSTRACT
Lithium–sulfur (Li–S) batteries have attracted considerable attention over the last two decades because of a high energy density and low cost. However, the wide application of Li–S batteries has been severely impeded due to the poor electrical conductivity of S, shuttling effect of soluble lithium polysulfides (LiPSs), and sluggish redox kinetics of S species, especially under high S loading. To address all these issues, a Ni–CeO2 heterostructure‐doped carbon nanofiber (Ni‐CeO2‐CNF) is developed as an S host that combines the strong adsorption with the high catalytic activity and the good electrical conductivity, where the LiPSs anchored on the heterostructure surface can directly gain electrons from the current collector and realize a fast conversion between S8 and Li2S. Therefore, Li–S batteries with S@Ni‐CeO2‐CNF cathodes exhibit superior long‐term cycling stability, with a capacity decay of 0.046% per cycle over 1000 cycles, even at 2 C. Noteworthy, under a sulfur loading up to 6 mg cm−2, a high reversible areal capacity of 5.3 mAh cm−2 can be achieved after 50 cycles at 0.1 C. The heterostructure‐modified S cathode effectively reconciles the thermodynamic and kinetic characteristics of LiPSs for adsorption and conversion, furthering the development of high‐performance Li–S batteries.
1 February 2013 in Materials Science and Engineering: A
Body-centred cubic (BCC) Ti–18Zr–13Mo (wt%) alloy displays excellent yield strength (≈800 MPa), stable hardening (rate > 1500 MPa) and uniform ductility >18%, resulting from multi-TWIP (multiple twinning-induced plasticity) strengthening effect. This multimodal mechanisms include micro-scale {332} deformation twinning (DT), nano-scale {112} DT and a rare {5 8 11} DT mode. Martensitic phase transformation is completely suppressed and the sample stays a single-phase solid solution throughout the deformation. In situ electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the multi-TWIP and dynamic Hall–Patch effect, with dislocation slip and large grain distortions at twin interfaces. GRAPHICAL ABSTRACT IMPACT STATEMENT The addition of Zr solutes stabilizes β Ti-alloy and completely suppresses phase transformations, allowing {332}, {112} and {5 8 11} multimodal twinning to give a better combination of strength, strain-hardening rate and ductility.