Journal of Materials Engineering and Performance最新文献

TiO₂ and TiO₂/HA composite coatings were successfully grown on Ti6Al4V-ELI (Extra Low Interstitial) alloys using the plasma electrolytic oxidation (PEO) method to improve the corrosion performance of the alloys. Three different high frequencies (1250, 1500, and 1750 Hz) were applied during the plasma electrolytic oxidation (PEO) of an electrolyte containing nano-hydroxyapatite (HA) particles to synthesize TiO₂/HA nanocomposite coatings. Additionally, conventional TiO₂-PEO coatings were produced at the same frequencies to compare their in vitro corrosion performance in simulated body fluid (SBF). The corrosion characteristics of the coatings were evaluated using the potentiodynamic polarization scanning (PDS) technique at 37 °C. The surface morphologies were examined with scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). X-ray diffraction (XRD) was used to determine phases on the surfaces. All coated samples had 2-5 times higher polarization resistance than the Ti6Al4V-ELI alloy. The highest corrosion-resistant coating was obtained in the nano-sized HA-containing coating grown at 1750 Hz.

The present study investigates the mechanical properties, corrosion behavior, and high-temperature oxidation performance of functionally graded weld joints (FGWJs) and conventional dissimilar weld joints (Conv. DWJs) between P91 steel and AISI 304 stainless steel. The Conv. DWJ, fabricated without a filler metal, exhibited thermal expansion mismatch, a higher rate of corrosion, and non-protective oxide layer formation. To overcome these issues, FGWJs were fabricated using an activated TIG welding process (A-TIG) incorporating an Inconel 625 interlayer. The FGWJs demonstrated superior tensile strength (556 MPa) and ductility (34.8%), achieving a joint efficiency of 85.40%, compared to Conv. DWJ (479 MPa and 6.88%) with a joint efficiency of 73.57%. The improved corrosion resistance (0.7 mpy of FZII in FGWJ compared to 1.99 mpy of Conv. DWJ) was attributed to the modified austenitic phase of the fusion zones of FGWJ. Impact toughness was also improved (132 J), and dilatometry results confirmed the reduction in thermal expansion mismatch. High-temperature oxidation tests at 800 °C revealed the formation of a dense internal Cr₂O₃ layer and an external nickel-rich layer, which collectively suppressed the growth of the thermally grown oxide scale. The oxidation kinetics in FGWJs followed a parabolic rate law, further confirming their robust performance. The adopted fabrication strategy enhanced the thermal and mechanical stability of FGWJs, supporting their application in high-temperature environments such as chemical plants and power generation systems.

The main objective of the present study is to investigate the shielding characteristics of charged particles, gamma rays, and fast neutrons for magnesium alloys. Despite the extensive utilization of these alloys in electromagnetic shielding applications, their radiation shielding properties are not available in the literature, to the best of our knowledge. Consequently, this study aims to address this knowledge gap by providing a comprehensive and comparative analysis of the radiation protective abilities of the alloys. To this end, the radiation shielding parameters are evaluated through the utilization of the PHITS, PAGEX, SRIM and Phy-X/PSD codes. Moreover, a comprehensive and comparative analysis of the results is conducted. Observations are made concerning the proportionality of shielding effectiveness for charged particles (protons and α-particles), neutrons and gamma rays, as a function of aluminum, copper, zirconium, lithium, tin, manganese, calcium, lanthanum, cerium, gadolinium, samarium and yttrium contents for binary, ternary and quaternary Mg alloys. It is determined that the alloys including contents of lanthanum, gadolinium, yttrium and samarium were characterized by enhanced levels of protective properties. Among the alloys, the highest protective feature is observed for Mg-Zn-Sm, Mg-La, Mg-Sm and Mg-Gd, respectively, and the lowest one is seen for Mg-Li, Mg-Al-Ca-Mn, Mg-Zn-Mn and Mg-Zn-Ca-Ce, respectively.

In this study, Cu-10Pb-10Sn/steel bimetallic samples were prepared using the solid-liquid composite method for Cu-10Pb-10Sn alloy. The friction and wear behavior of Cu-10Pb-10Sn alloy and GCr15 stainless-steel rings under various loads, sliding speeds, and lubrication media were systematically investigated using a ring-block friction testing device. Experiments were conducted under dry friction, kerosene lubrication, and oil lubrication conditions, focusing on the coefficient of friction, wear volume, wear rate, abrasive wear morphology, and wear surface characteristics. The wear mechanism of the Cu-10Pb-10Sn alloy under the different conditions was also analyzed. The results demonstrate that, under three working conditions—dry friction, kerosene lubrication, and oil lubrication—the wear rate and wear volume of the alloy vary differently with changes in load and rotational speed. Additionally, the friction mechanism evolves differently under each of these conditions. Under dry friction conditions, wear severity is reduced at high speeds. Under kerosene lubrication, the wear behavior is comparable at high speeds and high loads. Oil lubrication is more suitable for high-speed conditions. The combined multi-case tribological performance of Cu-10Pb-10Sn alloys demonstrates the best tribological performance under oil lubrication. This study provides a theoretical basis for the selection of lubricants and the optimization of lubrication conditions. Additionally, it provides practical guidance for the design and operation of piston pump components, while also advancing the development of lubrication technology in the field of tribology.

This paper analyzed the effects of heat treatment on microstructure and properties of ADC12 alloy containing Mo, Sr, and Al-5Ti-B by comparing the as-cast and heat-treated alloys. Results demonstrate that the alloy with Al-5Ti-1B has the most significant effect on grain refinement, while the alloy containing Sr has the best modification effect on eutectic Si phase. The eutectic Si phase size decreases significantly, and the shape factor of as-cast and heat-treated alloys increases to 0.83 and 0.85, respectively, which helps to enhance the overall properties of the alloy. Mo promotes the transformation of the Fe-rich phase into the AlFeMoSi dispersed phase and weakens its fragmentation effect on the matrix. The hardness of the heat-treated alloys increased 45.3 ~ 69%, with the alloys containing Al-5Ti-1B and Sr showing the most noticeable improvement. The melting and spheroidization of eutectic Si after heat treatment help to enhance the conductivity of alloy. Specifically, the conductivity of heat-treated alloys is more than 10% higher than that of as-cast alloys. After heat treatment and addition of varied compositions, ADC12 alloys have a low friction coefficient and wear rate, especially the alloy with Sr, which shows excellent wear resistance due to its fine and evenly distributed eutectic Si phase, and the friction coefficient is 0.47.

The single-stage aging (T6) and double-stage aging (T73 and T74) were conducted on the Al-Zn-Mg-Cu alloy obtained from backward extrusion. The precipitation behavior during the aging process and its effects on the corrosion resistance were comprehensively examined. The results indicate that the double-stage aging can greatly enhance the corrosion resistance compared to the single-stage aging. The grain boundary precipitates after T6 treatment are mainly composed of fine η′ phases with continuous distribution, and the width of the precipitation-free zone is narrow, resulting in the lowest corrosion resistance. The grain boundary precipitates after T74 are primarily composed of large, blocky, plate-like η phases that exhibit a dispersed distribution, and the width of the precipitation-free zone is large. Hence, the corrosion resistance of the T74 treated sample is superior, compared to those of T6 and T73. Moreover, double-stage aging can promote the segregation of Cu element at grain boundaries, thereby decreasing the anodic dissolution rate and effectively inhibiting the stress corrosion cracking.

To reveal the influence of microstructure and adiabatic shear band (ASB) characteristics on the ballistic performance of Ti-555 armored titanium alloy, microstructure and microscopic damage characteristics were analyzed by using optical microscope, scanning electron microscope, and electron backscatter diffraction. By comparing the target test results and observing the failure position on the target plates, it was found that the ballistic performance and the behavior of the crack propagation induced by the ASB were disparate in different microstructure types. Equiaxed and duplex microstructures have higher plasticity; the ASB and the matrix have better coordinated deformability, showing better ballistic performance. For Ti-555 titanium alloy, a faster cooling rate is beneficial for achieving better matching of strength and plasticity and promoting the deflection of the crack during propagation. At the same time, increasing the proportion of the β phase, the number of large-angle grain boundaries, and the aspect ratio of the α phase in the microstructure will be conducive to the improvement of the ballistic performance.

Magnesium alloy is a lightweight material widely utilized in aerospace, automotive, and structural sectors. However, its inherent drawback lies in its limited mechanical and wear resistance properties. Hence, the present study is conducted to investigate the influence of multiwall carbon nanotube particles on the microstructural, mechanical, and wear behavior of Mg nanocomposites. A specialized stir-squeeze casting method, complemented by ultrasonication, was employed for composite fabrication. Optical microscopy and high-resolution scanning electron microscopy confirmed the homogeneous distribution of nanoparticles within the Mg matrix. x-ray diffraction analysis verified the presence of nanoparticles and intermetallic phases, indicating thermal stability. Compared to the base alloy, the nanocomposites AC0.5, AC1, and AC1.5 exhibited significant improvements in hardness by 21, 49, and 37%; tensile strength by 8, 18, and 13%; compression strength by 6, 15, and 9%; and impact resistance by 3, 7, and 5%, respectively. Tribological properties were assessed using a pin-on-disk tribometer with an L16 orthogonal array. ANOVA showed that load was the most significant factor (58%), followed by sliding velocity (20%), sliding distance (12%), and temperature (10%). Adding 1% weight of MWCNT to the alloy improved the wear rate, coefficient of friction, wear depth, and surface roughness by 11%, 60, 12, and 59%, respectively.

This paper first conducted annealing experiments on SS400 steel at the critical phase transformation point using a continuous annealing simulator at various heating rates (e.g., 10, 30, 50, 100, 150, and 212 °C/s). Subsequently, utilizing techniques such as a tensile testing machine, optical microscope (OM), scanning electron microscope (SEM), and electron backscatter diffraction (EBSD), the effects of heating rate on the mechanical properties, microstructure, and texture of SS400 steel during critical phase transformation annealing were investigated. The results indicate that the heating rate has little effect on the mechanical properties of the experimental steel, such as yield strength, tensile strength, and n-value (strain hardening exponent), which are approximately 346 MPa, 460 MPa, and 0.16, respectively. However, when the heating rate reached 212 °C/s, the elongation significantly decreased to 20.4993%. Under different heating rates, the grain morphology of the experimental steel exhibited polygonal equiaxed shapes. As the heating rate increased, the average grain size increased from 7.33 to 8.87 μm. The {100} < 011 > rotated cube texture and {100} < 001 > cube texture first increased and then decreased, while the λ-fiber texture, Goss texture, and α*-fiber texture first decreased and then increased. When the heating rate reached 212 °C/s, the recrystallized grain orientations were predominantly λ- < 111 > //ND and Goss texture.

Wire arc additive manufacturing (WAAM) is a promising technique for fabricating large-scale, high-performance metal components. This study focuses on the fabrication of boiler-grade SS308L stainless steel walls using WAAM and evaluates their fracture toughness through single-edge notch bend (SENB) testing, a method for determining crack resistance. The measured fracture toughness of WAAM-fabricated SS308L reached 176.56 MPa√m, showing an 8.4% improvement over conventionally wrought (WR) SS308L (162.81 MPa√m). Detailed microstructural analysis was conducted to assess variations across build regions and their influence on crack resistance. Crack propagation behavior was further analyzed using generalized finite element method (GFEM), a numerical simulation technique for modeling fracture mechanics. The numerical predictions closely matched experimental outcomes, with deviations under 2%. The novelty of this work lies in the integrated experimental and numerical investigation of toughness behavior in WAAM-fabricated boiler-grade stainless steel, supported by microstructural correlation. The findings demonstrate the suitability of WAAM for high-integrity pressure components in thermal power and boiler application.