The crystal phase structure of cathode material plays an important role in the cell performance. During cycling, the cathode material experiences immense stress due to phase transformation, resulting in capacity degradation. Here, we show phase-engineered VO₂as an improved potassium-ion battery cathode; specifically, the amorphous VO₂exhibits superior K storage ability, while the crystalline M phase VO₂cannot even store K⁺ions stably. In contrast to other crystal phases, amorphous VO₂exhibits alleviated volume variation and improved electrochemical performance, leading to a maximum capacity of 111 mAh g⁻¹delivered at 20 mA g⁻¹and over 8 months of operation with good coulombic efficiency at 100 mA g⁻¹. The capacity retention reaches 80% after 8500 cycles at 500 mA g⁻¹. This work illustrates the effectiveness and superiority of phase engineering and provides meaningful insights into material optimization for rechargeable batteries.

Intermetallic gamma titanium aluminides display attractive engineering properties at high temperatures of up to 750 °C. To date, they have been used in low-pressure turbine blades and turbocharger rotors in advanced aircraft and automotive engines. This review summarizes the fundamental information of the Ti–Al system. After providing the development of $\gamma$TiAl alloys, typical phases, microstructures and their characteristics in TiAl alloys, the paper focuses on the effects of alloying elements on the phase boundary shifting, stabilizing effects and strengthening mechanism. The relationships between chemical additions, microstructure evolution and mechanical properties of the alloy are discussed. In parallel, the processing technologies and the common heat treatment methods are described in detail, both of which are applied to optimize the mechanical properties via adjusting microstructures. On this basis, the effects from chemical composition, processing technologies and heat treatments on microstructure, which controls the mechanical properties, can be obtained. It has a certain guiding significance for tailoring the microstructures to gain desired mechanical properties.

As a cathode material for potassium-ion batteries (PIBs), manganese-based layered oxides have attracted widespread attention due to their low cost, ease of synthesis, and high performance. However, the Jahn-Teller effect caused by Mn³⁺ and the irreversible phase transformation of the structure leads to poor cycle stability, limiting the development of layered oxides in PIBs. Herein, we demonstrate the use of phase-transition-free CaTiO₃ as rivets in K_0.5Mn_0.9Ti_0.1O₂ by a simple solid-state method. As verified by the in situ X-ray diffraction, the CaTiO₃ rivets effectively prevent the slippage of the transition metal layer during charge and discharge, inhibiting structural degradation. As a result, the obtained K_0.5Mn_0.9Ti_0.1O₂-0.02CaTiO₃ shows excellent cycling stability and rate performance, with high capacities of 119.3 and 70.1 mAh·g^-1 at 20 and 1000 mA·g^-1, respectively. At 200 mA·g^-1, the capacity retention remains 94.7% after more than 300 cycles. This work represents a new avenue for designing and optimizing layered cathode materials for PIBs and other batteries.

Cardiovascular disease is a leading cause of global mortality. Percutaneous coronary intervention, which involves the placement of stents to restore blood flow in narrowed arteries, is a widely used treatment. However, traditional stents, such as bare metal stents and drug-eluting stents, can lead to long-term complications such as restenosis, inflammation, and thrombosis. Biodegradable metallic vascular stents, with their superior mechanical properties, excellent biocompatibility, and gradual degradation in vivo, hold significant potential for the treatment of coronary artery disease. This review provides a comprehensive overview of the current research status and challenges. Firstly, it outlines the design principles and performance evaluation methods for biodegradable stents, which focus on mechanical properties, chemical characteristics, corrosion behavior, and biocompatibility. Furthermore, it summarizes the material features, degradation mechanisms, and metabolic behavior of three primary biodegradable metals—magnesium alloys, iron alloys, and zinc alloys—and discusses critical issues such as the degradation rate of different alloys and the development of zinc alloys. Finally, based on the current achievements and challenges of studies on biodegradable metal-based stents, this article proposes some optimization strategies and research prospects.

In situ heating transmission electron microscopy (TEM) was used to investigate the initial stage of γ‐TiAl lamellae formation in an intermetallic Ti–45Al–7.5Nb alloy (in at.%). The material was heat treated and quenched in a non‐equilibrium state to consist mainly of supersaturated, ordered α₂‐Ti₃Al grains. Subsequently, specimens were annealed inside a TEM up to 750 °C. The in situ TEM study revealed that ultra‐fine γ‐TiAl laths precipitate in the α₂‐matrix at ≈730 °C which exhibit the classical Blackburn orientation relationship, i.e. (0001)α₂//(111)γ and [$11{\bar {2}}0$ ]α₂//<110]γ. The microstructural development observed in the in situ TEM experiment is compared to results from conventional ex situ TEM studies. In order to investigate the precipitation behavior of the γ‐phase with a complementary method, in situ high energy X‐ray diffraction experiments were performed which confirmed the finding that γ‐laths start to precipitate at ≈730 °C from the supersaturated α₂‐matrix.