This work reports on a systematic investigation of the microstructure and comprehensive performance of Cu–Fe immiscible composite coatings prepared through the combination of mechanical alloying and laser cladding. The samples were characterized by scanning electron microscopy with an energy dispersive analysis, X-ray diffraction, a digital microhardness tester, a current tester, an electrochemical analyzer, and a magnetometer. The results show that the immiscible composite coatings are mainly composed of α-Fe particle dispersion in the ε-Cu matrix due to liquid phase separation, and this is exacerbated by the addition of more Fe content. Concentrated distribution of Fe-rich particles at either the top or bottom of the immiscible composite coatings is driven by the dominant mechanism of Marangoni and Stokes motion. With the increased fraction of Fe content, the microhardness and electrical resistivity increased, but with a degradation in corrosion resistance. With the increased ball milling time, the electrical resistivity increased, and the corrosion resistance improved. Compared to the medium-carbon steel substrate, the immiscible composite coatings can achieve an improved corrosion resistance, as well as a maximum saturated magnetization of 10.172 emu/g and the lowest coercivity at 17.249 Oe.

Nonequilibrium among phonon branches critically influences nanoscale heat transport yet remains largely unexplored in one‐dimensional (1D) systems, particularly at cryogenic temperatures. This work reports the first experimental quantification of optical–acoustic phonon coupling factor ( G _OA ) in single‐walled carbon nanotubes using the frequency‐domain energy transport state‐resolved Raman technique at cryogenic and room temperatures. Remarkably, a strong suppression of G _OA is observed at low temperatures that exceeds the suppression of the coupling of interfacial phonon modes. As temperature increases, G _OA is found to increase monotonically, consistent with enhanced anharmonic decay processes of optical phonons. At 93 K, the optical–acoustic phonon temperature difference exceeds 75% of the acoustic phonon temperature rise, which is reduced to about 33% at room temperature. The critical role of laser heating size on phonon nonequilibrium is elucidated, where it gets amplified for a more confined heating size. By utilizing the recently developed equivalent interfacial medium model, the intrinsic temperature‐dependent interfacial thermal conductance based on acoustic phonon temperature is obtained. The results show that neglecting the nonequilibrium among phonon branches overestimates the interfacial conductance by ≈30% at room temperature. This research provides fundamental insights into phonon nonequilibrium in 1D nanoscale materials that strongly impact next‐generation nanoelectronics and solid‐state energy converters.

The temperature coefficient of resistivity (θT) of carbon-based materials is a critical property that directly determines their electrical response upon thermal impulses. It could have metal- (positive) or semiconductor-like (negative) behavior, depending on the combined temperature dependence of electron density and electron scattering. Its distribution in space is very difficult to measure and is rarely studied. Here, for the first time, we report that carbon-based micro/nanoscale structures have a strong non-uniform spatial distribution of θT. This distribution is probed by measuring the transient electro-thermal response of the material under extremely localized step laser heating and scanning, which magnifies the local θT effect in the measured transient voltage evolution. For carbon microfibers (CMFs), after electrical current annealing, θT varies from negative to positive from the sample end to the center with a magnitude change of >130% over 125% within a length of ∼2 mm, uncovering strong metallic to semiconductive behavior change in space. Our θT scanning technique can be readily extended to nm-thick samples with μm scanning resolution to explore the distribution of θT and provide a deep insight into the local electron conduction.

This work investigated the mechanical and catalytic degradation properties of FeMnCoCr-based high-entropy alloys (HEAs) with diverse compositions and porous structures fabricated via selective laser melting (SLM) additive manufacturing for wastewater treatment applications. The effects of Mn content (0, 30 at%, and 50 at%) and topological structures (gyroid, diamond, and sea urchin-inspired shell) on the compression properties and catalytic efficiency of the Fe_80-xMn_xCo₁₀Cr₁₀ HEAs were discussed. The results indicated that an increase in the Mn content led to a phase structure transition that optimized mechanical properties and catalytic activities. Among the designed structures, the gyroid HEA structure exhibited the highest compressive yield strength, reaching 197 MPa. Additionally, Fe₃₀Mn₅₀Co₁₀Cr₁₀ HEA exhibited exceptional performance in catalytic degradation experiments by effectively degrading simulated pollutants with a significantly enhanced rate by 22.3% compared to other compositions. The Fe_80-xMn_xCo₁₀Cr₁₀ HEA catalyst fabricated by SLM demonstrated high stability over multiple cycles. These findings reveal that porous FeMnCoCr-based HEAs have significant potential for catalytic degradation of organic pollutants, providing valuable insights for future catalyst design and development in efficient and sustainable wastewater treatment.