Journal of Materials Engineering and Performance最新文献

The objective of this study is to create a composite material comprising pure Zr and Q345 steel with Ti foil as an interlayer, using the diffusion composite method. Four temperature gradients of Zr/Ti/Q345 steel composite plates were prepared in a vacuum hot press sintering furnace under vacuum conditions at diffusion temperature of 800-950 °C, pressure of 10 MPa and diffusion time of 2 h. The element diffusion, interface product composition, mechanical properties and electrochemical corrosion behavior of composite interfaces at different temperatures were investigated, and the diffusion mechanism and fracture failure mechanism of composite plates were analyzed. The thickness of the reaction layer at the composite interface increases with temperature, in which a dendritic structure is formed at the Zr/Ti interface and the dendritic structure plays a role in hindering crack extension, and ZrC and TiC layers are formed at the Ti/Fe interface, and the optimum shear strength can be obtained by controlling the thickness of the ZrC and TiC layers. The maximum shear strength of the composite plate was determined to be 208 MPa at 900 °C.

In order to investigate the microstructure evolution of Fe-30Mn-8Al-0.9C (wt.%) low-density steel after various solution treatment durations at 1050 °C, the growth behavior of austenite grain size and the precipitation of κ-carbides were systematically analyzed using optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and x-ray diffraction (XRD). The mechanical properties of the test steel were evaluated through tensile testing. The results indicate that the microstructure of the test steel after hot rolling and solution treatment was composed of austenite, ferrite, and κ-carbides. A significant number of annealing twins were observed following the solution treatment. When the solution treatment was conducted at 1050 °C for durations ranging from 30 to 120 min, the average size of κ-carbides increased from 0.15 μm to a maximum of 0.47 μm as the treatment time extended. The tensile strength and yield strength of the test steel in the as-rolled condition are highest, reaching 908 and 660 MPa, respectively, with an elongation of 30.20%. As the solution treatment time increases, both tensile strength and yield strength gradually decrease, while elongation initially increases and subsequently decreases. For the solution treatment at 1050 °C for 30 min, tensile strength and yield strength are measured at 826 and 442 MPa, respectively, with an elongation of 44.60%, resulting in a maximum strength–plasticity product of 36.83 GPa·%.

In this paper, the effect of print temperature on the microstructure, mechanical property, and warping deformation of polylactic acid (PLA) components prepared via fused filament fabrication (FFF) approach was investigated. The research focuses on PLA components with potential applications in biomedical implants and lightweight automotive parts. The surface morphology, microstructure, warping deformation, and mechanical properties of FFF-fabricated PLA components were detected utilizing scanning electron microscopy (SEM), x-ray diffraction (XRD), non-contact laser 3D scanner, and universal tensile testing machine, respectively. Additionally, COMSOL software was employed to simulate the heating process of PLA filaments at different temperatures, providing insights into the thermal behavior during fabrication. SEM observations showed that the surface morphology of FFF-produced PLA components obtained at 210 °C was more flat and smooth than those obtained at 190 °C and 230 °C, with reduced surface bulges and no scorching defects. The diffraction peak distribution in XRD results indicated that the FFF-fabricated PLA components prepared at 210 °C possessed the highest crystallinity (42%), which was 12% higher than that at 190 °C. The FFF-manufactured PLA components exhibited the smallest average warping deformation at 210 °C, with a value of 0.36 mm, representing a 16% decrease compared to 190 °C. In addition, the tensile strength of PLA components at 210 °C reached 53.8 MPa, which was 18% higher than that at 190 °C and 32% higher than that at 230 °C. These findings highlight the critical role of print temperature in optimizing the comprehensive performance of FFF-fabricated PLA components for practical engineering applications.

To enhance the corrosion resistance of soil contact machinery, FeCoNiCrMo HEA coatings were prepared on the surface of 65Mn steel using laser cladding technology, and nitriding treatment was carried out on this basis. The microstructure, phase composition, and hardness attributes of these coatings were meticulously examined through SEM, XRD, and nanoindentation methods. Findings indicate that following plasma nitriding, N has diffused into the material’s interior, with the diffusion depth and nitrogen content within the HEA coating exceeding those observed in the 65Mn steel. After the nitriding process of 65Mn steel, the surface predominantly comprises FeN_4. The coating of HEA predominantly comprises the FCC phase and the σ-Cr-Mo phase, supplemented by the presence of carbides. Compared with the HEA coating, the HEA composite nitriding coating forms FeN₄ and inhibits the formation of the FCC phase. Nitriding can increase the modulus of elasticity and nano-hardness of the materials, among which the HEA-coated composite nitrided samples showed the largest modulus of elasticity and nano-hardness of 206.37 and 16.49 GPa, respectively, which were 50.45 and 46.5% higher than that of the substrate, respectively. Kinetic potential polarization, EIS test, and immersion experiment were carried out in 0.5 M H₂SO₄ solution. The results show that both the HEA coating and the HEA composite nitriding coating have good corrosion resistance, among which the HEA coating has the best corrosion resistance. The self-corrosion current densities of both are relatively low, which are 0.00025 and 0.0015, respectively. The results of the immersion test show that there are large corrosion pits on the corroded surface of the substrate, while the corroded surfaces of the HEA coating and the HEA composite nitriding coating are relatively smooth.

This study investigates the evolution of microstructure and mechanical properties in a cold-rolled dual-phase Fe₄₀Cr₄₀Ni₂₀ medium entropy alloy consisting of face-centered cubic (FCC) and body-centered cubic (BCC) phases, following annealing at different temperatures. The solid solution state alloy encompasses the FCC phase within the BCC phase. After cold rolling and annealing at various temperatures, the same microstructural transformation that all alloys undergo can be summarized as follows. The original BCC phase transforms into a non-recrystallized BCC phase with a different chemical composition, accompanied by short strip-shaped FCC phases and long strip-shaped recrystallized BCC phases. The final evolved structure of the original FCC phase consists of an FCC matrix with Cr-rich BCC particles. The strength of the alloy decreases with increasing annealing temperature, primarily influenced by the volume fractions of FCC and BCC phases, residual dislocation strengthening post-annealing, grain refinement, and back stress arising from the heterogeneous structure. Ductility is mainly determined by the continuity of the soft region. These findings offer valuable insights and technical considerations for the design of dual-phase alloys with enhanced properties.

The corrosion and pitting behavior of 2A14 aluminum alloy exposed to the marine atmosphere for six months were investigated. This study provides novel insights into the corrosion mechanisms of 2A14 aluminum alloy under marine atmospheric conditions, which are critical for improving its corrosion resistance in such harsh environments. The results indicated that severe pitting corrosion occurred on the surface of the 2A14 aluminum alloy, with pitting corrosion being identified as the primary form of corrosion. According to XPS analysis, the main corrosion products on the sample surfaces after six months of exposure at three different marine sites were Al₂O₃, Al(OH)₃, and AlCl₃. Notably, the corrosion degree of samples exposed closer to the coast was significantly greater, highlighting the influence of proximity to the sea on corrosion severity. The charge transfer resistance of the material decreased with increasing exposure time, suggesting a progressive degradation of the material's surface resistance to corrosion. Importantly, the corrosion products formed on the alloy surface exhibited stronger protective properties than the natural oxide film, although their protectiveness initially increased and then decreased as the corrosion process continued. This finding is novel and has significant implications for understanding the complex interplay between corrosion products and the underlying alloy surface. The results of this study will help guide the design, fabrication, and evaluation of 2A14 aluminum alloy, especially for applications in marine environments, by providing a deeper understanding of its corrosion behavior and potential strategies for enhancing its durability.

In this study, selective laser melting (SLM) was employed to additively manufacture a newly developed reduced activation ferritic–martensitic (RAFM) steel at different scanning speeds (600, 800 and 1000 mm/s). Densities, hardnesses and wear properties of the SLMed specimens were examined with their microstructures characterized by x-ray diffraction, electron channeling contrast imaging, electron backscatter diffraction and energy-dispersive spectrometry. Results show that all these SLMed specimens consist of a mixture of ferritic and martensitic structures, along with many nanoscale precipitates. With increasing scanning speeds, the fraction and grain size of the ferrite increase gradually but the content of the precipitates is reduced. This makes the specimen hardness decrease from 392.3 to 352.2 HV as the scanning speed increases from 600 to 1000 mm/s. All the SLMed specimens have mainly experienced abrasive, adhesive and oxidative wear during the wear test, exhibiting considerably improved wear resistance compared to the conventionally prepared RAFM steel. Among the SLMed specimens, the 1000 mm/s specimen has the lowest hardness but the best wear resistance, which should be related to its specific heterostructure.

In this paper, 5083 Al/AZ31B Mg composite plates with added Ni foil were prepared by hot rolling, and the effects of Ni foil thickness (0, 5, 10, 25, and 50 μm) on the interface microstructure and the mechanical properties of the Al/Mg composite plates were investigated. The results show that the Ni foil added at the interface is fractured due to inhomogeneous deformation, showing a discontinuous band-like distribution at the interface. The presence of the Ni foil hinders the single interdiffusion between Al and Mg. Instead, a mixed interface composed of Al, Mg, and Ni forms, which is conducive to improving the interfacial bonding strength. Furthermore, the addition of the Ni foil interlayer contributes to the dynamic recrystallization of Al and Mg substrates near the interface, refining the grains at the interface, changing the grain orientation on the Al side and having a certain strengthening effect. As the thickness of the implanted Ni foil increases, the bonding strength and the tensile strength of the composite plate first increase and then decrease, and the largest values were obtained when the thickness is 25 μm, which are 5.9 N/mm and 245.25 MPa.

Improved electrical and reduced thermal conductivities are characteristics of desirable thermoelectric compounds. Incorporating nanostructures to Heusler alloys can enhance their performance as a thermoelectric material. The doping impact of annealed multi-walled carbon nanotubes (A-MWNTs) on the thermoelectric performance of half-Heusler alloys is examined and explained. Both NbFeSb-based and TiNiSn-based compounds have been investigated as a p-type and n-type, respectively. Thermal and electronic transport parameters were recorded at temperatures ranging from ambient to 875 K. The prepared samples are characterized using XRD, SEM, and EDAX. Utilizing TiNiSn-based samples, a promising figure of merit of 0.63 was obtained. The obtained thermoelectric results demonstrated that compositing the A-MWNTs with n-type compounds exhibited considerable impact on Seebeck coefficient and the electrical conductivity. However, for the p-type alloy, the variations in these thermoelectric parameters were dramatically less. It is hypothesized that the development of annealed carbon tubes as a conducting cluster in the n-type Heusler alloy could be one explanation for this variation. These promising findings will open the way for further research on CNT/Heusler composites as an effective power generation material.