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Abstract This work investigated the effect of hot isostatic pressing (HIP) on the corrosion behavior of Ti-6Al-4V samples prepared by electron beam powder bed fusion (EB-PBF). After the HIP treatment, the TiO2 content decreased but the growth rate of passivation films increased, leading to increase in internal defect density, thereby degrading the corrosion resistance. Amongst the different factors impacted by HIP including pore defects, β-phase, texture and morphology of α-phase, the morphology of α-phase played a dominant role in determining the corrosion performance of EB-PBF processed alloy.

Laser powder bed fusion (L-PBF) produced NiTi alloys have significant potential in biomedical applications. Varying the parameters of the L-PBF process may result in the NiTi alloys with different ratios of B2 and B19′ phases, thereby, the different corrosion performance in the human body. However, a dearth of research efforts remains dedicated to resolving this issue. This work employed three different but comparable sets of parameters in the L-PBF process to produce NiTi alloys with different ratios of B2 and B19′ phases. The corrosion behavior of samples in Hank's solutions with the addition of lactic acid and their evolution of passive films were investigated. The sample with the dominant B2 phase has a slower passive film formation rate and a higher corrosion rate than those with mixed B2/B19′ phases at the early film formation stage. As corrosion progresses, the passive films rapidly form within 24 h, followed by gradual degradation, represented by their varied charge transfer resistance. The degradation of passive films is attributed to the dissolution of NiO on the film surfaces, resulting from the hydration reaction. Such a phenomenon leads to imperfections in the passive films, diminishing their protective effectiveness for the underlying substrate. The sample with a faster film formation rate would also maintain a considerable corrosion resistance after film degradation. The presence of lactic acid accelerates the degradation of passive film and decreases the corrosion resistance of samples. This work advances the understanding of the relationship between the evolution of passive films and the processing parameters of L-PBF-produced NiTi alloys.

Rapid growth in industrial sectors such as automotive and shipbuilding has highlighted the significance of strip casting technology to produce lightweight alloys, particularly aluminum alloys widely used in both industrial production and daily life. Twin-roll casting (TRC), as an economically and environmentally friendly method for slab/strip production and processing, has attracted significant interest from researchers. However, the development of TRC aluminum alloys faces many challenges due to limited understanding of microstructural characteristics and control mechanisms. To further enhance comprehension of TRC aluminum alloys, this article reviews the influencing parameters, control methods, and existing issues related to TRC sub-rapid solidification (SRS) microstructure. It firstly summarizes TRC equipment types and their solidification characteristics, followed by a detailed analysis on key parameters affecting the evolution of TRC microstructure including rolling speed, roll separation force (RSF), and heat transfer coefficient (HTC). Finally, solutions to TRC defects are summarized and evaluated alongside their underlying mechanisms. This article provides a comprehensive review of the characteristics and control mechanisms of TRC microstructure while offering valuable insights for the future production of high-quality TRC aluminum strips.

Rock breaking has always been a challenging problem that must be solved in projects such as excavating mountains, drilling wells, and constructing railways. Among the rock-breaking cutter steels, AISI H13 steel and wear-resistant high manganese steel have become the best choices. From the characteristics and failure modes of the two, rock-breaking cutter steels should simultaneously have high strength, high toughness and high wear resistance to avoid short-term fracture/damage and cost increase. Analyzing the problems existing in the molding process of rock-breaking cutter steels such as die casting, forging, and hot stamping, traditional strengthening technologies such as alloying optimization, heat treatment, and surface treatment can achieve certain performance enhancement. After reaching the limits of traditional strengthening technologies, a series of nanoparticle strengthening technologies came into being. The selection, addition amount, and addition method of nanoparticles all affect the microstructure, mechanical properties and wear. To this end, this article summarizes the research progress and challenges of rock-breaking cutter steels, and discusses traditional strengthening technologies and mainstream nanoparticle strengthening technologies. It provides a reference for the future development of high-quality and high-performance rock-breaking cutter steels, with aim to simultaneously expand their application potentials to other fields.

The explosive growth of wireless communications and electronic devices has brought electromagnetic radiation's harmfulness and hidden trouble to light, which has a major impact on electrical equipment's ability to function normally. MXene, a material with favorable features like conductivity, a unique two-dimensional multiple-layer structure and abundant surface functional groups, has made it a viable contender for high-performance microwave-absorbers. This article introduces the synthesis strategy of MXene/MXene-based materials and their parent phase MAX, comprehensively summarizes and analyzes the current progress in the study on the microwave-absorbing properties of MXene/MXene-based materials, analyzes the main problems and bottlenecks. Future research directions for MXene microwave-absorbing are discussed in detail.

High‐entropy alloys (HEAs) are novel materials composed of multiple elements with nearly equal concentrations and they exhibit exceptional properties such as high strength, ductility, thermal stability, and corrosion resistance. However, the intricate and diverse structures of HEAs pose significant challenges to understanding and predicting their behavior at different length scales. This review summarizes recent advances in computational simulations and experiments of structure‐property relationships in HEAs at the nano/micro scales. Various methods such as first‐principles calculations, molecular dynamics simulations, phase diagram calculations, and finite element simulations are discussed for revealing atomic/chemical and crystal structures, defect formation and migration, diffusion and phase transition, phase formation and stability, stress‐strain distribution, deformation behavior, and thermodynamic properties of HEAs. Emphasis is placed on the synergistic effects of computational simulations and experiments in terms of validation and complementarity to provide insights into the underlying mechanisms and evolutionary rules of HEAs. Additionally, current challenges and future directions for computational and experimental studies of HEAs are identified, including accuracy, efficiency, and scalability of methods, integration of multiscale and multiphysics models, and exploration of practical applications of HEAs.

A Ti1.5Nb1Ta0.5Zr1Mo0.5 (TNTZM) refractory high entropy alloy (HEA) with a cellular structure was successfully fabricated by laser powder bed fusion (L-PBF). Compression testing and cyclic deformation testing results revealed that, in the cellular structure, the cell walls could store dislocations. Furthermore, the local chemical order (LCO) plays a crucial role in controlling dislocations within the cell wall region. The LCO not only facilitates dislocation slip but also generates additional lattice distortion upon stress-induced LCO destruction to enable dislocation pinning. This work offers novel insights into the microstructure of additively manufactured refractory HEAs and uncovers a distinct dislocation regulation mechanism.

Lattice structures show advantages in mechanical properties and energy absorption efficiency owing to their lightweight, high strength and adjustable geometry. This article reviews lattice structure classification, design and applications, especially those based on additive manufacturing (AM) technology. This article first introduces the basic concepts and classification of lattice structures, including the classification based on topological shapes, such as strut, surface, shell, hollow-strut, and so on, and the classification based on the deformation mechanism. Then, the design methods of lattice structure are analyzed in detail, including the design based on basic unit, mathematical algorithm and gradient structure. Next, the effects of different lattice elements, relative density, material system, load direction and fabrication methods on the mechanical performance of AM-produced lattice structures are discussed. Finally, the advantages of lattice structures in energy absorption performance are summarized, aiming at providing theoretical guidance for further optimizing and expanding the engineering application potential of lattices.

This work used electroshocking treatment (EST) plus external loading to regulate the microstructure of titanium matrix composites (TMCs). The external loading was 0.3 MPa. After EST plus external loading with 0.3 MPa, the α was reduced to 2.53 μm in size. The percentage of high angle grain boundaries (HAGBs) in α increased first and then decreased. The percent of HAGBs in TiB decreased, mainly due to the introduction of abundant dislocations in the TiB/matrix interface after EST. After EST, the maximum texture strength of TiB decreased from 13.09 to 12.97, and that of α decreased from 3.11 to 1.58. After EST under external loading with 0.3 MPa, the maximum texture strength of TiB decreased to 8.10. The orientation of TiB experienced significant variation. TEM results showed that TiB and α formed a distorted interface after EST under external loading with 0.3 MPa. The interplanar spacing of TiB and α was varied. All results show that the texture of TMCs can be relieved by EST plus external loading with 0.3 MPa. It is mainly attributed to the thermal and athermal effects and the imposed external loads with EST. EST plus external loading provides a new method for manipulating the microstructure of TMCs.

It is well known that the mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si are closely related to its microstructure and texture. In this work, a novel treatment of electroshocking treatment (EST) was adopted to optimize the microstructure and improve the mechanical properties of this titanium alloy. The grain orientation, texture, and mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy under EST were characterized and analyzed. With the increase of EST time to 0.04 s, the resultant acicular secondary αs shows a tendency of spheroidization and the increase in grain diameter, which leads to a little decrease in hardness and yield strength. The increase in EST time to 0.06 s resulted in the precipitation of martensitic phases with high aspect ratios and a reduction in grain size in Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy, as well as generating a more uniform texture distribution. The optimization of microstructure and texture significantly enhances the hardness and yield strength. The results in this work demonstrate that EST can serve as a novel method to regulate the microstructure and mechanical properties of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy.

Although introducing high porosity in biomedical Ti alloys can reduce their elastic modulus and promote new bone ingrowth, relieving the stress–shielding effect and implant failure, this also causes a decline in the alloys’ mechanical strength. In this work, a new preparation method for the high–strength and high–porosity Ti65Nb23.33Zr5Ta1.67Fe5 (TNZTF, at.%) alloy was suggested by sintering nanocomposite powder precursor in combination with the use of a space holder technique, in which NH4HCO3 is adopted to achieve a porous structure. The highly porous TNZTF alloy possesses a homogeneous fine–grained microstructure consisting of equiaxed α–Ti and a small amount of FeTi2, the latter of which is distributed in the β–Ti matrix. Through adjusting the mass fraction of NH4HCO3, a novel high–porosity, and high–strength TNZTF alloy with a low modulus was successfully prepared. The porous alloy with the addition of 30 wt.% NH4HCO3 exhibits a porosity of 50.3 ± 0.2%, a maximum strength of 327.3 ± 2.1 MPa, and an elastic modulus of 12.2 ± 0.3 GPa. The strength enhancement is mainly attributed to the unique fine–grained microstructure, which is obtained by the crystallization of the amorphous phase and the ductile–brittle mixed fracture mechanism. The prepared porous TNZTF alloy possesses higher mechanical strength and well–matched elastic modulus, showing great potential as an implant material.