In recent years, the development of material genetic methods, together with multi-scale material design theory and calculation methods has provided new ideas for the alloy design of novel Co-based superalloys. Based on the published results of multi-scale design and the research work of our laboratory, this paper systematically summarizes the present research status of multi-scale design methods in the field of novel Co-based superalloys. A review of multi-scale calculation methods including first-principle calculation, CALPHAD, phase field simulation, and machine learning is presented in this paper. The development trend of multi-scale design in novel Co-based superalloys is prospected.

Owing to the high temperature resistance, excellent high temperature oxidation and corrosion resistance, low density and production cost, Ni₃Al-based intermetallic alloys have broad applications and attract much attention. In order to widen the application field of the Ni₃Al-based superalloy, it is urgently important to improve the high-temperature performance on the basis of good weldability. Under this background, in the composition design of Ni₃Al alloy, the high Fe and Cr contents can effectively enhance the phase composition and weldability of Ni₃Al-based intermetallic alloys. Based on this, the microstructural characterization and phase separation sequences during solidification of a newly designed multiphase Ni₃Al-based intermetallic alloy modified with high Fe and Cr elements are analyzed. On account of the typical solidification structure of the multiphase Ni₃Al-based intermetallic alloy comprising γ'+γ dendrite, interdendritic β and γ'-envelope, etc., the microstructural evolutions of the alloy under different solution cooling rates, high temperature annealing, and long-term ageing processes are summarized. The effects of its corresponding complex microstructural variables (size of primary γ' phase, morphology of β, phase evolution in the interior of β, widening of γ'-envelope) on the creep behaviors of the multiphase Ni₃Al-based intermetallic alloy are systematically discussed. Recent advances in welding and joining of multiphase Ni₃Al-based intermetallic alloy are summarized, and the development of multiphase Ni₃Al-based intermetallic alloy is also prospected.

Additive manufacture is recognized as a world-altering technology which triggered a world-wide intensive research interest. Here the research progress and application of the laser additive manufacturing maraging steel (MS) are systematically outlined. The advantages of selective laser melting (SLM) additive manufacture of MS is emphasized. The processing parameter and properties optimizations, build orientation based anisotropies, age hardening mechanism, gradient materials, and applications in die and moulds of SLM-processed MS are reviewed in detail. Achieving relative density of >99% in SLM-processed MS is effortless, owing to the wide SLM process window of MS. Mechanical properties of MS produced with optimized SLM processing parameters and post heat treatments are comparable to traditionally wrought parts. The build orientation hardly affects the property anisotropies of MS. The age hardening behaviour in MS follows Orowan bowing mechanism. MS-based gradient multi-materials (such as MS-Cu, MS-H13, etc.) with high bonding strength are fabricated by SLM, which provides a new approach to produce high-performance functionally gradient multi-materials components. Lastly, the application in conformal cooling moulds of SLM-processed MS is elucidated, and future research interests related to MS are also proposed.

Addition of small amount of boron (B) in the (9~12)%Cr martensitic heat resistant steels can obviously prohibit the Ostwald ripening of M₂₃C₆ carbides so as to improve creep strength as well as creep rupture life. With the purpose of taking full advantages of B element, it is critical to make B preferentially distribute in (9~12)%Cr martensitic heat resistant steels. The mechanism of B preventing M₂₃C₆ carbides from ripening is also on the premise of clearly identifying the preferential distribution of B in the steels. Much concern has been growing over the preferential distribution of B in the research of (9~12)%Cr martensitic heat resistant steels. Therefore, this article gives a review on this aspect. Following a summary of the effect of B on mechanical properties, several commonly used characterizing methods for B segregation in the steels are introduced. Based on the physical metallurgy and the solution, diffusion mechanisms of B element, discussions on the preferential distribution of B element at prior austenite grain boundaries and in the M₂₃C₆ carbides as well as the related factors are emphasized. At last, two prevalent mechanisms of B restraining the coarsening of M₂₃C₆ carbides in (9~12)%Cr martensitic heat resistant steels are given by an intensive explanation so that the relationship between the preferential distribution of B and its advantage of increasing creep performance by suppressing the ripening M₂₃C₆ carbides are systematically elaborated, which gives a deep understanding of the role of B element in (9~12)%Cr martensitic heat resistant steels.

By contacting amorphous semiconductors with metals, amorphous semiconductors can be induced to transform into crystalline semiconductors at extremely low temperatures, a phenomenon known as metal-induced crystallization (MIC). Thin-film crystalline semiconductor is one of the key materials in many advanced technologies, and is widely used in the fields of microelectronics, optoelectronics, display technology and photovoltaic technology. MIC provides a new route for the production of crystalline semiconductor thin-films devices at low temperature, for fabrication of nanoporous metal materials and for interface engineering of metallic materials, and has therefore attracted wide interests from both academic and industrial communities. This paper reviews the current research progress of metal-induced crystallization of amorphous semiconductors at low temperatures, and the MIC behaviors in different metal/amorphous semiconductor systems are also classified and summarized. The thermodynamics and kinetics of MIC were calculated and analyzed in detail, highlighting the role of interface thermodynamics in the solid-solid phase transformation of thin-film systems. On this basis, the underlying mechanism of MIC has been elucidated. Finally, the future research trends of MIC are prospected.

A hybrid technique of additive manufacturing and subtractive process has provided a new solution combining product design and control by software. Wire arc additive manufacturing (WAAM) process wins well-respected because of its low cost and high efficiency of deposition, nevertheless the process has its limitation of high heat input and low forming accuracy. A new process of additive manufacturing with high efficiency of modeling is urgent needed which can control heat transfer, mass transfer and force transfer. To overcome the disadvantage upon, various hybrid manufacturing techniques have been developed with high efficiency and controlled modeling in recently. The machining process in hybrid manufacturing has more different characteristics from traditional material removal processes, such as residual stress and heat in the blank. These influence the whole efficiency of the hybrid manufacturing. The primary aim of this paper is to explore the feasibility of thermal machining during this process and make rational use of additive manufacturing in order to obtain optimal accuracy.

Epitaxy technique has been widely used for semiconductor, ferroelectric and optical materials in the development of electronic and optoelectronic devices. Epitaxial structures with strain and defects may tune the physical properties or affect the performance of devices. High-resolution X-ray diffraction (HRXRD) has significant advantages over traditional XRD with the features of small divergence, monochromatic incident beam and high resolution detection of the diffracted beam. It is a key technique for accurate characterization of epitaxial structures in non-destructive way. In this paper, the techniques of HRXRD for epitaxial film structure characterization are outlined in terms of the relationship between diffraction and reciprocal space, the difference between high-resolution diffraction and powder diffraction such as the optical system and the geometry mode of scanning etc. Based on the corresponding relationship between the epitaxial film and the matrix structure in the reciprocal space, various factors affecting the shape of the diffraction spots are analyzed, including the state of lattice match in coherence and non-coherence, super lattice and inclined growth. The other effective factors are also demonstrated, such as finite size of film, tilt and strain of epitaxial film etc. Real examples, such as Si_1-xGe_{x(x=0.1) etc., are used to explain how to obtain the structure parameters of the epitaxial films by HRXRD spectrum analysis, including lattice constant, lattice mismatch, thickness and superlattice information. To obtain more epitaxy information, reciprocal space map (RSM) analysis can be feasibly used by reconstruction of a series of HRXRD patterns. By combining HRXRD spectrum and RSM, microstructure characterizations of PbTiO3 epitaxy films, such as micro-strain, domain structure, phase transformation can be quantitatively analyzed.}

Potential functions are extensively applied in molecular dynamics (MD) simulation of metals. Selection of them is a very important step in MD simulations due to its effects of the precision and reliability of the simulations. They are one of the most important reference data during the process of calculation. In order to cover the shortage of pairwise potentials for modelling transition metals, EAM/FS many-body potentials have been introduced since 80's of last century. For the sake of determining parameters in the EAM/FS potential functions of bcc and fcc crystals through macro mechanical properties, relations between the EAM/FS potential functions and elastic constants were investigated in this work. Expressions of the pressure (P) and the bulk modulus (B), elastic constant (C₄₄) and shear elastic modulus (C_p=(C₁₁-C₁₂)/2) in terms of the embedding function, pair potential function and the electron density distribution function were deduced for bcc and fcc structures, respectively. It was found that the magnitude of the C₄₄ and C_p depends on the distances between the considered atom and surrounding atoms, but also the configuration of surrounding atoms. Finally, by converting five fitting equations about the cohesive energy (u_tot) and P, B, C₄₄, C_p into an optimization model of finding minimum value, the values of the six undetermined parameters in the cohesive energy were given for five typical bcc crystals (V, Mo, Nb, Ta and W) and three typical fcc crystals (Cu, γ-Fe, Ni), respectively. For each crystal, calculation errors show accuracy of parameter values. The obtained calculation results, for the minimum cohesive energy and the corresponding atomic distance, fit well with the reported experimental data, by adopting the above values of the parameters, which indicates the effectiveness for our method.

With the rapid development of rail transit, high-speed trains are gradually exported to Southeast Asian countries. Aluminum alloy is widely used as a structural material such as train body and rail beam in high-speed trains, so that it is important to study the corrosion behavior of different aluminum alloy in Southeast Asia. The exposure test was conducted on 5083, 6063 and 7020 aluminum alloys in Bangkok, Thailand for 1 a. SEM, XPS, electrochemical experiment and scanning Kelvin probe force microscopy (SKPFM) were used to study the corrosion morphology and corrosion mechanism of different aluminum alloys. The results showed that the corrosion potential of 6063 aluminum alloys were relatively high, about -0.66 V (vs SCE), and the corrosion morphologies were relatively mild, which was due to less alloy elements such as Mg, Si and Fe in the 6063 aluminum alloys. The corrosion rate of 6063 aluminum alloys in Bangkok, Thailand was about 0.7 g/(m²·a). 7020 aluminum alloy contains more Zn elements, and the corrosion potential was about -0.78 V (vs SCE). The corrosion rate was the highest, about 3.26 g/(m²·a). The second phase of Fe-Si-Al or Fe-Si(Mn)-Al formed in the microstructure of the three aluminum alloys. The surface potential of the second phase was higher than that of the matrix, about 225~280 mV. In the atmospheric environment, the second phase acted as the cathode phase, and the surrounding matrix Al dissolved preferentially. The second phase fell off and formed a pit.