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Because of its excellent wear resistance and corrosion resistance, CoCrFeNi-based HEA has been selected as the coating prepared on steels to improve its service life. This paper presents single-track CoCrFeNiMo 0.2 Nb 0.2 HEA cladding layers fabricated at different laser scanning speeds on an AISI H13 steel substrate. The grain morphology, microstructure and elemental distribution are illustrated. The phase constituents of the fusion zone (FZ) and middle section of the coatings were analyzed. The outcomes of this research showed that as the laser scanning speed increased, the grains in the cladding layers were refined, while the variation in the Fe elemental content first increased and then decreased. In the FZ, Mo and Nb, as strong carbide-forming elements, preferentially combined with the carbides in the substrate, forming a new (Mo)NbC phase with a grain size of 600 nm at the retained austenite grain boundary. During the process of laser cladding, the thermal Marangoni flow of multiple principal components and the solidification of the molten pool, which are influenced by the scanning speed, determine the microstructure of the (Mo)NbC in the FZ and eutectic in the in-between section of the cladding layer. The illustration of the microstructure evolution and solidification mechanism in this study can provide a foundation for the potential applications of HEA coatings. [Display omitted] • The single-track CoCrFeNiMo 0.2 Nb 0.2 HEA cladding layers were prepared on an AISI H13 steel. • The Mo, Nb elements in fusion zone prefer to form (Mo)NbC with a size of 600 nm at the retained-austenite grain boundaries. • The microstructure evolution from substrate to cladding layer is austenite, retained-austenite + (Mo)NbC, and eutectic. [ABSTRACT FROM AUTHOR]

Nanocrystalline multi-main-phase (MMP) Nd-Ce-Fe-B magnet can effectively suppress the magnetic dilution effect of Ce. However, its low coercivity and poor thermal stability have not been adequately overcome. In this work, a novel low-melting-point Gd 60 Y 10 Cu 15 Al 15 alloy was introduced into MMP Nd-Ce-Fe-B magnet through intergranular addition for simultaneously enhancing its coercivity and thermal stability. The results show that the intrinsic coercivity H cj is obviously improved, and its maximum increment is ∼12.3 % at 4 wt% Gd 60 Y 10 Cu 15 Al 15 alloy. Especially, the increase in H cj is more significant, and an abnormally increase in the maximum energy product (BH) max occurs at high temperature of 150 °C. Meanwhile, the reversible temperature coefficients of H cj (β) and B r (α) are improved simultaneously. These findings imply the enhanced thermal stability for the MMP magnet with Gd 60 Y 10 Cu 15 Al 15 addition. The microstructural characterizations, compositional analyses and micromagnetic simulations reveal that the competitive effects of the formed non-ferromagnetic grain boundary (GB) phase and Y or Gd diffusion into the main phase lead mainly to a synergistic improvement in the coercivity and thermal stability of the magnet. This work is expected to provide a promising cost-effective approach for developing the high-performance thermally-stable Nd-Ce-Fe-B magnet and explore more possibilities for effective utilization of Y or Gd rare-earth resources. • The Research Highlights in this paper are as follows: • A novel low-melting-point Y-Gd based alloy was developed and used to modify the nanocrystalline MMP Nd-Ce-Fe-B magnet. • H cj and thermal stability of nanocrystalline MMP magnet are synergistically enhanced. • Microstructure evolutions and composition distributions are revealed. • The enhanced mechanisms for H cj and thermal stability are systematically analyzed. [ABSTRACT FROM AUTHOR]

To enhance the wear resistance of nickel-based superalloys and broaden their applications, we investigated the microstructural organization and wear properties of IN718 composites reinforced with graphene nanoparticles fabricated through selective laser melting. The optimal parameters for printing were obtained by combining experiments and simulations, and their wear patterns were subsequently explored at different sliding speeds (250–350 r/min) and loads (4N–8N). Based on the composite TEM images combined with experiments, it was found that the homogeneous dispersion of graphene nanoparticles in the 3D-printed GNPs/IN718 composites acted as dislocation reinforcement and load reinforcement. The average microhardness of the GNPs/IN718 composites increased by 24.2 % compared to the IN718 alloy. In the friction test, GNPs acts as a lubricating phase, resulting in a significant increase in the friction wear performance of the composite. The average coefficient of friction decreased by 33.8 % and the wear rate decreased by 51.3 %. The wear state of the composites change from abrasive wear to delamination wear and a combination of delamination wear and oxidative wear as the speed and load are increased, respectively. This paper provides potential guidance for further improving the wear performance of additively manufactured nickel-based superalloys. • Flow-3d software simulations combined with experiments were used to verify the optimal parameters for printing. • The homogenous dispersion of GNPs improve the wear resistance of the composite. • Graphene nano-platelets reinforced IN718 matrix composite was fabricated by SLM. • The wear state changes from abrasive wear to delamination and oxidative wear as conditions change. [ABSTRACT FROM AUTHOR]

Due to the low production cost and light weight, copper-clad aluminum conductors show great potential value in the field of power transmission, while the phase structure and organizational changes at the Cu–Al interface in high-temperature environments have a great impact on the electrical and mechanical properties. In this paper, Cu–Al diffusion couples are prepared to study the diffusion process, microstructure, and growth kinetics of intermetallic compounds (IMCs) in Cu–Al interface during heating from 600 °C to 800 °C, and the mechanical and electrical properties of Cu–Al diffusion couples are discussed. The results show that after heat treatment, IMC layers are formed at the Cu–Al interface and the Al-side is composed of CuAl and CuAl 2 , in which the CuAl phase transforms from long to thick dendrites with the increase of temperature, and finally grows into a "popcorn" form. The IMCs at the Cu–Al interface from the Cu side to the Al side are in the order of Cu 3 Al layer, Cu 9 Al 4 layer, Cu 3 Al 2 layer and CuAl layer, among which the Cu 3 Al 2 layer is the thickest (168.42 μm at 700 °C), while the Cu 3 Al layer is the thinnest (37.32 μm at 700 °C). The kinetic calculations show that the diffusion layer grows up rapidly, which is caused by the generation of liquid-phase during the heating process, leading to the acceleration of the diffusion of Cu and Al. The kinetic factor of the Cu 3 Al 2 layer is the largest (n = 0.69), causing the fastest growth rate of the Cu 3 Al 2 layer, while the Cu 3 Al layer shows the largest activation energy for diffusion and the smallest diffusion rate (Q = 9.48 kJ/mol, D 0 = 2.06 × 10−1 m2/s), therefore its growth rate is the slowest. Based on the thermodynamic calculations and the Cu–Al phase diagram, a growth mechanism of the Cu–Al interface is proposed, the formation sequence of IMCs at the Cu–Al interface is Cu 9 Al 4 , CuAl, Cu 3 Al 2 and Cu 3 Al. The formation of IMCs layer at the Cu–Al interface leads to a significant increase in the hardness of Cu–Al samples (the hardness of the Cu 3 Al 2 is 10 times higher than that of Cu) and an obvious decrease in electrical conductivity (the electrical resistivity of Cu–Al is 5 orders of magnitude higher than that of Cu), affecting its application in the electrical industry. • Cu 3 Al, Cu 9 Al 4 , Cu 3 Al 2 , and CuAl were formed in the Cu–Al interface at 600°C–800 °C. • Cu 3 Al 2 layer has the excellent kinetic factor (n = 0.69) and the growth rate. • The formation mechanism of IMCs in the Cu–Al interface at 600°C–800 °C is proposed. [ABSTRACT FROM AUTHOR]

Silicon carbide/metallic glass interpenetrating phase composites (SiC/MG IPCs) have attracted great attention due to their superior performances. However, the effect of the interface on the mechanical properties remains unclear. In this paper, three SiC three-dimension network scaffolds (SiC 3D-NSs) with different volume fractions and surface areas were firstly prepared by selecting SiC particles of different sizes, and the corresponding SiC/MG IPCs were further prepared using vacuum pressure infiltration and water quenching. The microstructure and mechanical properties of the scaffolds and related IPCs were studied. The SiC and MG phases are continuous, mutually interpenetrated in 3D space. The strength of the scaffolds and related IPCs are positively correlated with the SiC volume fraction. It is found that partial crystallization of MG occurred at the interface due to the increase in interface thermal resistance and heterogeneous nucleation. During compression or bending, such the interfacial structure can retard the main crack propagation by initiating a large number of secondary cracks. It contributes to an apparent increase in the crack propagation path, significantly improving the fracture toughness of IPCs. This result shows that interface engineering in IPCs is of great significance for improving their toughness. • The SiC/MG composites containing interpenetrating architectures were fabricated using a pressure infiltration technique. • The interfaces in the composites will increase interfacial thermal resistance and theMG will crystallize at the interface. • The crystallized phase at the interface is more likely to induce crack extension, which will increases the toughness. [ABSTRACT FROM AUTHOR]

In this paper, porous NiTi intermetallic was synthesized via a modified thermal explosion (TE) method, utilizing Ni (74 μm, 38 μm, 5 μm, 100–200 nm) and Al element powders as raw material. The exothermic behavior and phase transition of porous NiTi intermetallic compounds were studied. The results showed that with the refinement of Ni particle size, the heat release decreased, and the Ti-74 μm sample was the product of two eutectic reactions. Their mechanical properties were verified by the Vickers hardness tester and universal testing machine, and the corrosion behavior of porous NiTi intermetallic compounds in phosphate-buffered saline (PBS) solution was studied by electrochemical tests. Among them, Ti-5 μm exhibits the most homogeneous microstructure and favorable mechanical properties, which has a porosity of 31.7 % and a compressive strength of 321.71 MPa. However, corrosion resistance is sacrificed due to the high open porosity. This study holds great promise for precise control microstructural characteristics and optimization of mechanical and electrochemical properties of porous NiTi intermetallics. • Porous NiTi intermetallic compounds were sintered by a rapid TE method. • The refinement of the particle size will limit the heat release of the TE reaction. • The prepared NiTi has a porosity of 31.7 % and a compressive strength of 321.71 MPa. • Reducing porosity contribute to improving corrosion resistance. [ABSTRACT FROM AUTHOR]