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CrNx/Ag nanocomposite films with varying Ag content were prepared by reactive magnetron sputtering under a constant Ar/N2 stream. The films were annealed between 500 – 800 °C in the air. The microstructure and elemental composition of films were studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. The mechanical properties were characterized with respect to nano-hardness and high-temperature tribology. The results reveal that the incorporation and concentration of Ag influence the morphology and microstructure of films. The microstructure of films evolves by annealing, and the films with higher Ag concentration exhibit more severe structure evolution. Annealing at 650 °C results in the sublimation of Ag, and the oxide emerges on the film surface. Annealing at 800 °C reveals that the film with 6.2 at.% Ag exhibits superior structural stability, while the one with 20.2 at.% Ag deteriorates. The hardness of films decreases with the increasing Ag concentration and heating temperature. Films with 12.6 at.% Ag and above possess solid lubrication during the sliding at 350–650 °C. Both the friction coefficient and wear resistance are found dependent on the Ag concentration and sliding temperature.

The influence of annealing time and secondary-rolling reduction ratio on grain boundary character distribution (GBCD) in an FCC CoCrFeMnNi high-entropy alloy were investigated via electron backscatter diffraction (EBSD). The results show that the processing of 10% cold-rolling reduction subsequently with annealing at 1073 K for 10 h induces a high frequency of low coincident site lattice (CSL) boundary with >70%, thereby effectively achieving GBCD optimization. As annealing time increases, low-Σ CSL (Σ ≤29) boundary frequency first decreases and then remains constant at approximately 60%. The secondary-rolling reduction ratio followed by annealing at 1073 K for 10 h also exerts a substantial influence on GBCD. As the reduction ratio increases from 6% to 40%, the low-Σ CSL (Σ ≤29) boundary frequency first increases and then decreases.

The Ti(C, N)-TiB2 composite cermets with different binders (HEAs or Ni-Co) were fabricated by mechanical alloying and vacuum hot-pressing sintering. Wear resistance of two composite cermets at elevated temperatures was studied. Wear mechanism was characterized by a combination of scanning electron microscopy and energy dispersive spectroscopy. Experimental results indicated that HEAs binder composite cermets possessed excellent wear resistance comparing with Ni-Co binder composite cermets. At lower temperatures, no obvious difference was observed in worn surfaces of two cermets. Abrasive wear mechanism was dominant wear mechanism. At greater than 600 °C, oxidative wear and adhesive wear were found to be dominant wear mechanism. The wear rate of HEAs binder composite cermets was 11.8%, 17%, 39.25%, and 46.7% lower than that of Ni-Co binder composite cermets at 200℃, 400℃, 600℃, and 800℃, respectively. Enhanced wear performance of Ti(C, N)-TiB2-HEAs composite cermets is attributed to relatively high hardness and toughness, as well as excellent high-temperature softening resistance and oxidation resistance of HEAs.

Cerium–lanthanum mixed rare earth (RE) (0.5 wt.%) was added to Zn-20Sn high-temperature lead-free solder to study the effect of RE on the solder properties. The Zn-20Sn-0.5RE solder has a better corrosion resistance than that of Zn-20Sn alloy. RE addition increases the γ-Cu5Zn8 layer thickness, promotes growth of a e-CuZn5 layer shaped like bamboo shoots, and increases the roughness of the e-CuZn5 layer, which increases the shear strength of the solder joints. Compared with the Zn-20Sn alloy, the creep resistance of the Zn-20Sn-0.5RE solder was improved after soldering. The indentation hardness increases in an order of Zn-20Sn-0.5RE solder, Zn-20Sn solder, e-CuZn5 layer, and γ-Cu5Zn8 layer.

In the present work, 0.2 wt% Ni and 0.1–0.5 wt% RE (Ce and La mixed rare-earth) were added into Zn–20Sn high-temperature lead-free solders. The effects of Ni and RE additions on the microstructure and properties of the solder alloys were investigated. The results show that with the increase of RE content, the solidus temperature of the solder alloys does not change much, but the liquidus temperature decreases, and the wettability and microhardness of the solder alloys increase. Adding Ni or RE element individually does not change the IMC layer structure at the solder/copper interface, but it affects the growth of the IMC layer. That is, the addition of Ni inhibits the growth of the interface IMC layer, and the addition of RE promotes the growth of the IMC layer.

Akaganeite, with the formula FeO(OH,Cl), has potential in the realms of environmental protection, energy conversion/storage, and biomedicine. However, its large-scale production is still challenging in terms of cost and environmental friendliness, which limits its commercial application. In this study, we report a one-step sonochemical fabrication method to address this challenge. Fabrication has been performed in aqueous FeCl3 solutions with the aid of acoustic cavitation by gas bubbles. The fabricated FeO(OH,Cl) nanoparticles (NPs) are porous and exhibit spindle shapes. With increasing sonication time, these NPs can be spontaneously assembled to form irregular micro-/nanostructures of varied sizes. When required, such assemblies could be suitably directed by adding appropriate templates, either natural or artificial. The template-directed assembly relies on the principle of minimum free energy and the resulting FeO(OH,Cl) NPs nucleating and growing along the added templates. This study demonstrates a sonochemical fabrication method amenable to large-scale production, that is inexpensive and environmentally friendly, providing monodisperse porous FeO(OH,Cl) NPs of spindle shape and their various assemblies for commercial purposes.

CrNx/Ag multilayer coatings and a comparative CrNx single layer were deposited via reactive magnetron sputtering. In multilayer coatings, the thickness of each CrNx layer was constant at 60 nm, while that of the Ag layer was adjusted from 3 to 10 nm. Microstructure of the films was characterized by X-ray diffraction and transmission electron spectroscopy. The results suggest that the film containing 3 nm of Ag layer presents a nanocomposite structure comprising fine nano-grains and quasi-amorphous clusters. With Ag layer thickness reaching 4.5 nm and above, Ag grains coalesce to produce continuous an Ag layer and exhibit (111) preferential crystallization. Hardness of the films was detected by nanoindentation and it reveals that with increasing the Ag layer thickness, the hardness continuously decreases from 30.2 to 11.6 GPa. Wear performance of the films was examined by the ball-on-disk test at 500 °C. The result suggests that the out-diffusion of Ag towards film surface contributes to the friction reduction, while the wear performance of films depends on the thickness of the Ag layer.

Ti(C, N)-TiB2 composite cermets with different binders (high entropy alloy (HEA) or Ni-Co) were fabricated by mechanical alloying and vacuum hot-pressing sintering. The wear resistance of the two composite cermets at elevated temperatures was studied. Wear mechanism was characterized by a combination of scanning electron microscopy and energy dispersive spectroscopy. The experimental results indicated that HEA binder composite cermets possessed excellent wear resistance comparing with Ni-Co binder composite cermets. At lower temperatures, no obvious difference was observed in the worn surfaces of two cermets. Abrasive wear mechanism was dominant wear mechanism. At greater than 600 °C, oxidative wear and adhesive wear were found to be dominant wear mechanism. The wear rate of the HEA binder composite cermets was 11.8 %, 17 %, 39.25 %, and 46.7 % lower than that of the Ni-Co binder composite cermets at 200 ℃, 400 ℃, 600 ℃, and 800 ℃, respectively. The enhanced wear performance of Ti(C, N)-TiB2-HEA composite cermets is attributed to relatively high hardness and toughness, as well as excellent high-temperature softening resistance and oxidation resistance of HEA.

The equiatomic refractory high entropy alloy (HEA) TiZrNbMoTa was investigated. The alloyed powders with face-centered cubic (FCC) structured solid solution phase were prepared by mechanical alloying (MA) and then sintered by spark plasma sintering (SPS) at 1300, 1400, 1500, and 1600 °C. The microstructure and mechanical properties of the bulk alloy were investigated. The body-centered cubic (BCC) structured solid solution phase and the ZrO2 phase precipitated from the FCC structured solid solution phase during cool-down from sintering. The highest compression fracture strength (3759 MPa) and fracture strain (12.1%) were obtained in the refractory HEA sintered at 1400 °C. The grain boundary strengthening, precipitation strengthening, solid solution strengthening, transformation-induced plastic (TRIP) effect, and toughening effect of the ZrO2 phase are the important factors for the high strength and ducitily of the refractory HEA prepared in this study.

CrNx/Ag multilayer coatings and a comparative CrNx single layer were deposited via reactive magnetron sputtering. In multilayer coatings, the thickness of each CrNx layer was constant at 60 nm, while that of the Ag layer was adjusted from 3 to 10 nm. Microstructure of the films was characterized by X-ray diffraction and transmission electron spectroscopy. The results suggest that the film containing 3 nm of Ag layer presents a nanocomposite structure comprising fine nano-grains and quasi-amorphous clusters. With Ag layer thickness reaching 4.5 nm and above, Ag grains coalesce to produce continuous an Ag layer and exhibit (111) preferential crystallization. Hardness of the films was detected by nanoindentation and it reveals that with increasing the Ag layer thickness, the hardness continuously decreases from 30.2 to 11.6 GPa. Wear performance of the films was examined by the ball-on-disk test at 500 &deg, C. The result suggests that the out-diffusion of Ag towards film surface contributes to the friction reduction, while the wear performance of films depends on the thickness of the Ag layer.

The FeCoCrNiAl high-entropy alloys (HEA) was used as binder of the Ti(C, N)–TiB2 composite cermets. The Ti(C, N)–TiB2–FeCoCrNiAl HEA composite cermets were successfully fabricated by mechanical alloying (MA) and vacuum hot-pressing sintering (VHPS) at different sintering temperatures. The microstructure, room-temperature hardness, fracture toughness, bending strength, high-temperature hardness and oxidation behavior were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers hardness testing, indentation method, three point bending method, high-temperature vacuum hardness testing and cyclic oxidation. For the Ti(C, N)–TiB2-HEA composite cermets, apart from Ti(C, N) and TiB2 phases, also a minority Fe2B were detected in the XRD patterns. TEM observation revealed that the structure of the HEA binder was a solid solution where the Ti(C, N) and TiB2 were tightly bound. The Ti(C, N)–TiB2 composite cermets with a Ni/Co binder was selected as a reference. The experimental results indicated that the composite cermets with the HEA binder possesses excellent oxidation resistance. This is attributed to the formation of a continuous and dense external oxide scale and TiO2 layer that effectively impede inward oxygen transport, which leads to a remarkable improvement in the oxidation resistance. The Ti(C, N)–TiB2-HEA composite cermets sintered at 1500 °C showed excellent fracture toughness of 7.9 ± 0.1 MPa.m1/2. And the Ti(C, N)–TiB2-HEA composite cermets sintered at 1550 °C showed excellent hardness and bending strength of 1977.3 ± 20 HV10 and 768.6 ± 20 MPa, respectively. The high-temperature hardness of the HEA binder composite cermets was 993.7 ± 30 HV20, which was superior to the Ni/Co binder value of 668.1 ± 30 HV20 at 1000 °C.