Abstract Galvanic corrosion can cause significant damage on aerospace structures due to mixed material components and aggressive operating environments under atmospheric conditions. Predicting both the galvanic corrosion magnitude and distribution is important to help inform the design and maintenance of new and existing structures, respectively. Prior efforts have developed atmospheric models for risk mapping, but validation has been in the form of simulated atmospheric environments in the lab, rather than actual corrosion processes in outdoor environments, with the latter being more representative of operational conditions for aerospace components. Therefore, the present work investigates the development and validation of an atmospheric model predicting the galvanic corrosion magnitude and distribution that is expected to occur in outdoor conditions.

Abstract The individuals listed here provided reviews for the papers in Volume 14 of Materials Performance and Characterization (MPC). As the Editor-in-Chief, I would like to express my appreciation to the reviewers for their time and efforts in reviewing papers for MPC. Constructive criticism from reviewers provides support to authors and maintains the high quality of the journal. Their generosity is much appreciated, and I hope your association with the journal continues in the future. Dr. Richard W. Neu Georgia Institute of Technology Atlanta, GA, USA Babak Abazadeh Magd Abdel Wahab Mushtaq Albdiry Ganesh Bhaskaran T. T. Dele-Afolabi Jesiya Susan George Andrew Gryguc Jianfeng Gu Jomon Joy Ismail Hakkı Kara G. Suresh Kumar Xin Li Demofilo Maldonado Michael Mannahan, Sr. Hamed Mirzadeh Sridhar Niverty Nikita H. Patel Prashanta Patra Laura Pena-Paras Bojan Podgornik Rupesh Rajendran Farshid Sadhegi Johan Schuurmans Ashutosh Sharma Pawandeep Singh Giribaskar Sivaswamy Christopher Solomon Meurig Thomas Di Wu Venu Yarasu Patricia Zambranor Borut Zuzek

Abstract This study investigates the elevated temperature mechanical behavior of Ti-5V-5Mo-5Cr-4Al alloy through uniaxial tensile experiments conducted at temperatures ranging from room temperature to 550°C and strain rates of 0.001, 0.01, and 0.1 s−1. The results reveal that the dominant softening mechanism is dynamic recovery, whereas dynamic precipitation took place at the lowest rate of deformation and at temperatures ranging from 400°C to 500°C. To predict the mechanical behavior of this recent beta titanium alloy, artificial neural network (ANN) approach and modified Hensel-Spittel (m-HS) model were employed. In the prediction of flow curves using the m-HS model, a correlation coefficient (R) of 0.901 and an average absolute relative error (AARE) of 8.891 % were obtained. In contrast, the ANN approach yielded significantly better results, with an R value of 0.997 and an AARE of 2.3 %. The findings from this study provide routes for determining the hot workability of next-generation metastable beta titanium alloys.

Abstract Magnesium and its alloys are considered promising materials for temporary bio-implants because of their mechanical properties, which closely resemble those of natural bone. Higher rates of corrosion and degradation in the physiological environment always limit its practical application as an implant. Extensive research is being conducted to reduce the effect of corrosion on implants. This study dwells on the experimentation of the application of zein-hydroxyapatite-based composite coating on the magnesium AZ31B alloy and the dip coating technique to achieve the coating. The experimental results provide insights into the dip coating technique and also provide the effect of corrosion after the coating. Additionally, the composite coating’s structural and compositional characteristics are analyzed to assess its suitability for biomedical applications. The research concludes by discussing the effects, merits, and demerits of the coating technique and how the zein-hydroxyapatite coating affected the corrosion properties of the alloy.

Abstract In this study, stainless-steel 316L samples were fabricated by the laser powder-bed fusion (L-PBF) process under three distinct printing parameter sets, namely, varying scan speeds while maintaining other parameters fixed. The samples were categorized according to their volumetric energy densities (VEDs) as high, medium, and low conditions, which were all included in the range of achieving high relative density. Detailed characterizations of melt pool geometries, grain morphologies, and crystallographic textures were conducted along with Vickers hardness measurements and anodic polarization tests on specific planes of the printed specimens. Results indicated that the crystallographic texture was significantly influenced by the VED, with a preferential orientation of {100} <001> observed in the high VED condition, whereas both medium and low VED conditions displayed a mixed texture of {100} <001> and {110} <001>. The high VED promoted the formation of deeper and wider melt pools embedded with larger, irregularly shaped grains, whereas the medium and low VEDs resulted in narrower melt pools and smaller grain morphologies. Notably, the medium VED generated uniformly stacked melt pools with a periodic stripe pattern, featuring <001> grains aligned at the centerline and <011> grains at the edges, achieving the most accurate depth-to-width ratio according to given input parameters. Such variations in texture and grain morphology directly affected the mechanical responses, whereas differences in grain size governed the corrosion properties in each characteristic direction, depending on the printing strategy. Hereby, highly anisotropic mechanical and corrosion behaviors in the printed material were induced. The critical role of VED or scanning speed in controlling the microstructural characteristics and hardness of L-PBF 316L samples was highlighted.

Abstract This research presents the effects of heat treatment on rolling contact fatigue (RCF) life and corrosion performance of stainless-steel Pyrowear 675 (P675). P675 was heat treated using two heat treatment (HT) processes with an order of magnitude difference in total cycle time. They are identified at a short heat-treated (SHT) cycle and long heat-treated (LHT) cycle. The carburized specimens from both HT were tempered at 316°C (low temperature tempered [LTT]) and 496°C (high temperature tempered [HTT]). The HT and tempered P675 samples were evaluated for RCF life using a ball-on-rod tester at a maximum Hertzian stress of 5.5 GPa in a hybrid configuration (with silicon nitride rolling elements) and at a temperature of 218°C, using gas turbine engine type II ester oil conforming to MIL-PRF-23699 G, Performance Specification: Lubricating Oil, Aircraft Turbine Engine, Synthetic Base, Nato Code Numbers: O-152, O-154, O-156, and O-167. The corrosion resistance was evaluated using electrochemical impedance spectroscopy (EIS) in simulated synthetic seawater. The heat treatment cycle has a significant effect on microstructure, corrosion resistance, RCF life, and wear performance. The SHT cycle with both tempers resulted in carbide necklacing at grain boundaries and lower carburized case depth. The longer heat treatment cycle showed superior RCF life and lower wear rate compared to the shorter heat treatment cycle. However, the shorter heat treatment cycle showed improved corrosion resistance. Post test analysis showed significant differences in microstructural changes between HTs.

Abstract Magnesium alloys are promising lightweight structural materials, but their poor corrosion resistance limits broader application. This study investigates the corrosion performance and microstructural evolution of a novel EZ43 magnesium alloy enriched with rare-earth elements (Cereium [Ce] and neodymium [Nd]). The samples were prepared by extrusion and subjected to corrosion testing in Hank’s solution to simulate physiological conditions. Electrochemical impedance spectroscopy, potentiodynamic polarization, and hydrogen evolution tests were performed alongside surface characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD). Results revealed that Ce and Nd additions improved corrosion resistance and promoted the formation of a more stable protective layer. Among the samples, EZ43B exhibited the lowest corrosion current density (Icorr) and hydrogen evolution rate, indicating superior corrosion performance. These findings suggest that RE-doped EZ43 alloys offer significant potential for biomedical applications where lightweight and corrosion-resistant materials are required.

Abstract This work investigates the deformation behavior of porous specimens under different conditions during upsetting. The preforms were prepared through a powder metallurgy technique for various amounts of titanium, such as 2 %, 4 %, and 6 % in the aluminum under different percentages of initial relative densities, like 80 %, 85 %, and 90 %, with one aspect ratio by suitable loads. The sequence of compression tests was conducted at room temperature and various forming parameters were determined. The metal flow was investigated using the DEFORM-2D tool at different step numbers, and we observed that the flow of metal started from the head surface to the equatorial surface, and fracture arose in the outer sectors of the specimen due to the higher stresses and the lower density. Therefore, the deformation behavior of the component was affected. This work is intended to increase the forming characteristics of the produced preforms by adopting the selective heating mechanism at the equatorial zones of the deformed specimen. Heating selectively at the damaged place of the samples could increase the true strain, decrease the true stress, increase the densification, increase the damage parameter, and increase the grain size of the components due to releasing stresses, materials softening, dynamic recrystallization, reduction of porosity amount, and change in microstructure.

Abstract The effect of surface crack size on the strength of 15CDV6 steel parent metal and weldments has been studied in hardened and tempered conditions. Residual strength (σr) and apparent fracture toughness (KIe) in the presence of surface cracks are important inputs to the designers to prevent catastrophic failure during service. A surface crack tension (SCT) test has been carried out by introducing different crack sizes on the parent metal and weldments of 6-mm-thick 15CDV6 steel plates and compared with defect-free material. The maximum reduction in strength was found to be 5.5 % when compared with the ultimate tensile strength (UTS) of the parent metal. Similarly, for weldment, it was found to be 3.6 % for crack sizes up to 7 × 2.4 mm. It was also found that in the parent metal, with a range of a/B ratios from 0.23 to 0.44, the σr was found to vary from 1,074 MPa to 1,018 MPa. Similarly, for a/B ratios varying from 0.23 to 0.47, σr ranges from 1,031 MPa to 964 MPa for weldments. This indicates that 6-mm-thick 15CDV6 steel is not prone to brittle fracture for surface crack sizes up to 8.2 × 2.2 mm in the case of the parent metal and 7.5 × 2.1 mm for weldment. The range of KIe values obtained for parent metal varies from 50 MPa√m to 82 MPa√m and for weldments from 47 MPa√m to 78 MPa√m. The fractography of SCT test specimens reveals the presence of fine dimples, which are indicative of ductile fracture. The obtained results were compared with high-strength steels like Maraging (M250) and 0.3C-CrMoV(ESR) in the parent metal and welded conditions.

Abstract This study investigates the synthesis of pure and nickel (Ni)-doped cadmium sulfide nanoparticles (CdS NPs) using an ultrasonic wave irradiation (sonochemical) technique with varying Ni doping concentrations (0.05 %, 0.1 %, and 0.15 %). This process results in the formation of agglomerated nanoparticles with precise structural characteristics. X-ray diffraction (XRD) analysis reveals particle sizes ranging from 16 to 31 nm that are consistent with nanoscale measurements. XRD and particle size analysis indicate an average particle size of less than 32 nm. Energy dispersive X-ray analysis confirms the successful incorporation of nickel ions. Additionally, the optical properties, such as absorption, were measured, and the energy band gap of the prepared samples increased from 2.78 eV for pure CdS to 2.81 eV, 2.82 eV, and 2.89 eV for 0.05 % Ni: CdS, 0.10 % Ni: CdS, and 0.15 % Ni: CdS, respectively. Key electrical parameters, such as electrical conductivity, mobility, and carrier concentration, as identified by electrochemical impedance spectroscopy, were also enhanced. The efficiency of the fabricated cells with CdS and Ni: CdS were 2.188 %, 2.225 %, 2.288 %, and 2.349 %, respectively, for 0 %, 0.05 %, 0.10 % and 0.15 % Ni doping concentrations. The impact of nickel ions on the photovoltaic performance of CdS NPs was then investigated.