Electrodeposited nickel coatings often exhibit poor bond strength, cracks, and porous microstructure, which increases their susceptibility to corrosive environments; therefore, additional surface modification is required. This study proposes a hybrid surface treatment that combines nickel coating with laser shock peening (LSP), using different laser energies (2.5, 3.0, and 3.5 J) and impact scan (1, 2, and 3) to enhance corrosion resistance and mechanical properties. The results show that plastic deformation induced on the nickel coating creates densification through compaction and improves adhesion strength between the coating and substrate. LSP produced beneficial compressive residual stresses (CRS) with a maximum value of-657 MPa, which promotes the closure of surface defects, thereby enhancing coating integrity. The coating displayed an increase in hardness, rising from 160 HV to 487 HV under the highest impacts. The LSP-treated sample exhibits superior scratch resistance, with a reduction of 56.07% in scratch depth compared to the untreated nickel sample. After LSP, the electrochemical response of the Ni coating was significantly improved, with the corrosion rate decreasing from 12.285 mpy to 0.020 mpy. In addition, the passivation potential range was broadened, confirming a better stability of the passive layer. These enhancements are attributed to the synergistic effects of the ultrafine gradient structure and CRS, which improved scratch resistance and suppressed corrosion progression. The proposed hybrid method not only safeguards the coating but also offers a practical and adaptable approach for engineering applications.

The prospect of La0.8Ca0.2Mn1–xCoxO3 (0 ≤ x ≤ 0.3) perovskite oxides as magnetocaloric effect (MCE) based magnetic refrigerant has been explored. A phenomenological model has been employed to investigate various magnetocaloric properties, including magnetic entropy change (∆S), heat capacity change (∆C), full width at half band width (δTFWHM), adiabatic temperature change (ΔTad) and relative cooling power (RCP) through the study of temperature dependence of magnetization. Using this model, the magnetocaloric property values are predicted by calculating the magnetization data under varying external magnetic fields. Since magnetization reduces abruptly near TC a significant change in magnetic entropy change, heat capacity change and adiabatic temperature change occur. We observe as the doping concentration increases an enhancement in the predicted values of magnetocaloric parameters occur with the increasing magnetic field possibly due to the switching of the magnetic phase transition (MPT) in the material from first to second order. Thus, the results highlight the compounds as strong contenders for cooling applications across a broad range around room temperature. Moreover, the analysis affirms the extent of validity of the phenomenological model.

The current study investigates the corrosion resistance of pure copper modified through a hybrid technology involving surface coating and ultrasonic shot peening (USP) treatment. USP has been utilized to treat the electrodeposited nickel coating on copper under varying peening durations (30, 60, and 90 s) and the number of shots (12, 9 and 6). The effect of peening on the nickel-coated copper was investigated by potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) analysis using a 3.5 wt% NaCl aqueous solution. Additionally, the hydrophobic nature of the modified surface was examined by measuring the contact angle, which determines their ability to repel against the liquid. The potentiodynamic polarization analysis results show that increasing peening duration and number of shots increase the corrosion resistance of the peened nickel-coated samples. The corrosion current density of unpeened nickel coating of 2.033 mu A/cm2 was reduced to 0.016 mu A/cm2 by USP. Due to the impact of peening, the film resistance increased from 10,720 S2-cm2 to 51,815 S2-cm2 and the rest of the EIS results revealed similar patterns in corrosion behaviour. USPeened samples can effectively eliminate surface pores, reduce grain size, and induct compaction of the coating layer, resulting in a more stable passive film layer on the peened surface. Thus, the novel innovative approach involves unique parameter settings and surface treatment conditions that significantly enhance the material properties, resulting in an improvement in the electrochemical properties.

In this study, dissimilar metals, such as aluminium (AA5083) and galvanised interstitial free steel, were laser-brazed in a flange configuration using eutectic filler aluminium wire (4047, Al-12%Si). To investigate the effects of wire deposition rate on the characteristics of laser-brazed joints and to understand the factors contributing to corrosion in these joints. The wire deposition rates were varied while keeping other laser parameters constant. Changes in wire deposition rate were observed to affect the flow behaviour of molten metal leading to variations in the geometrical characteristics of the brazed joints and interfacial reactions as revealed by macroscopic examination. A series of corrosion tests, including electrochemical, immersion, and salt spray tests, were conducted on the laser-brazed joints. It was demonstrated by Immersion corrosion tests that the wire rate influenced the corrosion results for the laser-brazed joints. However, the salt spray test showed no substantial effect on corrosion with respect to different wire deposition rates. Furthermore, the electrochemical results indicated significant changes in the corrosion response of the brazed zone due to the presence of chemically dissimilar phases. A correlative discussion between laser parameters, observed microstructure, and their effects on the corrosion performance of the brazed samples is presented.

The ultrasonic shot peening (USSP) technique is being utilized as a reliable post-treatment process for various industrial parts to protect them from failures in their respective functions. The current study aims to develop nearly 10-microns-thick Ni-Cr alloy coatings to protect mild steel via a fast galvanic pulse deposition method and to enhance their mechanical and electrochemical properties through the different USSP process parameters as a hybrid technique. The morphological studies show the closure of cracks, better hardness, and scratch resistance of coatings after peening. XRD analysis confirms the presence of compressive residual stresses, along with the grain refinement and texturing effect after peening. After USSP, due to the presence of dimples average surface roughness has been increased up to 5 microns. The closure of pores and cracks and the hydrophobic nature of the coatings helped it to gain better corrosion resistance.

The ultrasonic shot peening (USSP) technique serves as a reliable post-treatment method for various industrial components to prevent functional failures. This study aims to develop hybrid Ni claddings approximately 300 mu m thick on mild steel using laser cladding (LC) and USSP techniques. Morphological studies reveal that the claddings exhibit enhanced closure of cracks, increased hardness, and improved scratch resistance after peening. XRD analysis confirms the presence of compressive residual stress, as well as grain refinement and texturing effects after the peening. Furthermore, the research endeavors to improve their mechanical and electrochemical properties by employing USSP's varied process parameters in a hybrid approach. After undergoing USSP treatment, the average surface roughness was increased by up to 6 mu m due to the formation of dimples, while it was 8 mu m in the as-cladded and only 1.5 mu m after polishing. Furthermore, compared to the as-cladded and polished claddings, the hybrid claddings exhibit a hydrophobic character linked to improved corrosion resistance and better in-depth roughness profiles.

The current research aims to develop a hybrid surface engineering process combining electrodeposition and ultrasonic shot peening (USP) to enhance surface-mechanical properties and coating strength. A thin nickel coating was deposited on the copper substrate through an electrodeposition process and the coating contained few microcracks and pits. The obtained coating was ultrasonically shot peened with different peening times and the number of peening shots (balls). The microstructural evolution, phase analysis, surface hardness, and scratch resistance of nickel coatings and peened coatings were characterized and discussed. The impact of peening based on duration and quantity of shots (ball), which induced grain refinement and compressive residual stress on the surface of the coating has been investigated. The multi-impact shots at a high velocity strike the coated surface and reduce the thickness of the electrodeposited nickel, creating better adhesion. The peening treatment resulted in enhancing the microhardness of the coated nickel from 123 Hv to 328 Hv. The tensile residual stress of coated nickel has been converted into compressive nature. The plastic deformation developed on the coated surface by USP and other factors lowered the coefficient of friction and enhanced the scratch resistance of the coating. Based on the result, it was established that USP has a broad and effective strengthening approach for the nickel coating deposited on soft substrate to increase its compactness and strength.

Elevated temperature plasma nitriding of Cr-Mo-V-based tool steel was performed by varying the treatment time to enhance hardness and wear resistance. Steel samples after metallographic polishing were placed on the conducting substrate holder in the nitriding reactor and evacuated to 0.5 Pa pressure. The sample holder was then negatively biased at 250 V to accelerate the ions toward the surface of the samples. A gas mixture of N2 and H2 was then passed into the vacuum chamber to generate the plasma. After plasma generation nitriding was performed at variable temperatures 500 and 550 °C for 6 and 10 h. Then X-ray diffraction (XRD) and Scanning Electron Microscope/Electron Dispersive Spectroscopic (SEM/EDS) studies were followed to understand the structural modifications. XRD analysis predicted the presence of iron nitrides, whereas SEM/EDS had shown the presence of N availability from the surface to the core of the steels. Following the structural characterization hardness and wear resistance were measured by using Vicker's microhardness tester and ball-on-plate method, respectively. It was found that the hardness, case depth, and wear resistance of the steel were significantly enhanced mainly due to nitrogen solid solution and nitride formation. Thus, it has been proved that a longer time or higher temperature of nitriding may be beneficial for such improvement.

In the present study, the effect of ultrasonic shot peening (USSP) on electrodeposited Ni/Ni-TiO2 coatings on mild steel substrate was analyzed in terms of surface-mechanical and electrochemical properties. USSP was performed on the Ni/Ni-TiO2 coatings surface deposited mainly from Watt baths with varying peening vibrational amplitude and peening time, and the resulting hybrid coating was analyzed using XRD, SEM, microhardness, scratch test, and corrosion analysis. The XRD analysis revealed a prominent texturing effect and residual compressive stress, which resulted in changes in surface-mechanical and corrosion properties. SEM morphology revealed pore closure following USSP, as well as a positive effect at the coating interface. Surface roughness and dimple size also had an impact on the properties. Microhardness and scratch results showed improvement after peening. The noticeable effect of peening was observed during a corrosion study using potentiodynamic polarization and EIS analysis.

•Effect of ultrasonic shot peening parameter on bilayer metallic coating was studied.•Improvement in surface-mechanical properties observed.•Noticeable improvement in residual compressive stress due to peening.

The article briefly describes the chronological progress of the Department of Metallurgical and Materials Engineering, National Institute of Technology (NIT) Rourkela from the 1960s till date. The rich history of the department along with the present status, particularly the focus on academia and research has been enumerated with milestones, facts, and figures.

The present study is aimed to analyze the influence of ultrasonic shot peening (USP) on 316L stainless steel both experimentally and analytically. The steel was ultrasonically shot-peened with varying peening parameters in terms of shot diameter and peening time with the primary aim of coverage of a certain area. The obtained samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness tester, and scratch tester. Improved hardness and residual compressive stress were observed after peening. A new analytical model has also been proposed for impact frequency prediction considering the movement of spherical shots inside the peening chamber using equations of motion. The outputs found through experiments supported the analytical results, which verified the validity of the analysis. It is thus established that the developed model can efficiently optimize the process parameters.

The influence of Ca + Bi on the tensile and strain hardening behaviour of the AZ91 alloy at ambient and elevated temperatures have been examined. The values of YS are higher, and ductility is lower of all the modified alloys. The UTS of the modified AZ91 alloys is lower except at 473 K. The UTS values decrease with an increase in test temperature for all the alloys. The improved YS of the modified alloys is owing to reduced grain size. The brittle Mg3Bi2, Al2Ca and Bi3Ca5 phases in the modified alloys reduce their UTS and ductility. The transgranular cleavage fracture at 298 K changes to quasi-cleavage fracture at 473 K. Several dislocations piled up around the β-Mg17Al12 and Al2Ca phases are seen.

TiO2 and ZrO2 nanoparticles reinforced Ni–W-based composite coatings were prepared on mild steel substrate via pulse electrodeposition technique under constant operating parameters. During the deposition process, TiO2 content was maintained constant throughout the process whereas, ZrO2 content has been varied. Phase evolution, microstructure, and compositional changes of coatings were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive microscopy, respectively. Microhardness and wear tests were conducted on composite coatings to evaluate the surface mechanical properties. The corrosion behaviour of the composite coatings was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. The topography of certain composite coatings has been examined by an atomic force microscope (AFM). Besides, a wettability test was conducted to study the hydrophobic properties of composite coatings. Experimental results demonstrated that ZrO2 nanoparticle's addition under fixed TiO2 content in deposition bath play a crucial role to improve the surface-mechanical, corrosion, and hydrophobic properties of the coating. The maximum hardness (1074 HV0.05), wear and corrosion properties were observed in Ni–W-5g/L TiO2-15g/L ZrO2 composite coating.

The corrosion responses of the individual and combined Ca and Bi incorporated AZ91 alloy are investigated through the immersion, hydrogen evolution, and electrochemical tests. All the modified alloys exhibit better corrosion resistance than the base AZ91 alloy. The AZ91 + 1.0Ca (wt%) alloy unveils better corrosion resistance than the AZ91 + 0.5Bi (wt%) alloy owing to the Al2Ca phase formation. The combined Ca and Bi added AZ91 alloys acquire better corrosion resistance than the individual Ca or Bi added AZ91 alloys. The AZ91 + 2.0Ca + 0.5Bi (wt%) and AZ91 + 1.0Ca + 1.0Bi (wt%) alloys exhibit the lowest and the highest corrosion rates among the combined additions. (c) 2021 Elsevier B.V. All rights reserved.

Recently, High entropy alloys (HEAs) advanced into high-temperature applications as potential candidates by enduring high temperatures with high thermal stability, higher oxidation and corrosion resistances, thermal fatigue, and creep resistances. HEAs acquire unique characteristics called core effects of HEAs: high entropy effect, sluggish diffusion effect, severe lattice distortion, and cocktail effect. HEAs frequently exhibit remarkable properties because of having such unique core effects. Thus, the emergence of HEAs has gained significant interest in the field of materials leading to a contemporary point of discussion on their exciting nature and properties. The current review article intends to summarize the significant works on the oxidation behavior of High entropy alloys (HEAs). Also, peculiar attention has been invested in comprehending oxidation behavior of HEAs in the viewpoint of the crystal structure that is BCC-HEAs, FCC-HEAs and few case studies were compared with the conventional alloys. Current challenges and essential future directions in this field are also pointed out.

The present investigation deals with the microstructural modification following the Bi + Sr additions to the squeeze-cast AZ91 alloy and its effect on impression creep response. The Bi + Sr additions form the Al 4 Sr and Sr 2 Bi phases besides the α-Mg and β-Mg 17 Al 12 phases, and improves creep resistance of the AZ91 alloy. The AZ91 + 1.0Bi + 0.5Sr alloy reveals the best creep resistance among the alloys. The stress exponent and the activation energy values of all the alloys are in the range of 4–7 and 100.2–112.7 kJ mol −1 , respectively, depicting the pipe diffusion-controlled dislocation creep is the governing creep mechanism. The post-creep microstructural study confirms several dislocations pile-ups around the Al 4 Sr and Sr 2 Bi phases resulting in improved creep resistance of the modified AZ91 alloys.

The present work investigates the effect of SiC nanoparticle additions on corrosion response of the squeeze-cast AZ91 + 2.0Ca + 0.3Sb (wt.%) alloy subjected to immersion, hydrogen evolution, and potentiodynamic polarization scan in a 0.1 M NaCl solution. All the AZ91 + 2.0Ca + 0.3Sb + xSiC(np) (x = 0.5, 1.0, 2.0 (wt.%)) nano composites demonstrate a superior corrosion resistance than the alloy, and the nanocomposite reinforced with 2.0SiC(np) exhibits the highest corrosion resistance. The improved corrosion performance of the nanocomposites is attributed to the decrease in the potential difference between alpha-Mg and beta-Mg17Al12 phases, reduced quantity of beta-Mg17Al12 phase, and an increased amount of Al2Ca phase following SiC nanoparticles additions.

Pure Cr and Cr-WC coatings are electrodeposited by both direct current (DC) and pulse current (PC) methods. The deposition was carried out with different (0, 3 and 5 kHz) pulse frequencies with varying nano-sized tungsten carbide (WC) loading (0, 3, 5 and 7 g l(-1)) of the electrolytic bath. X-ray diffraction (XRD) results of the coatings display Cr coating with BCC structure along with minor WC peak after the enlargement of the peaks. Scanning electron microscope (SEM) images depict uniform and finer morphology for the coatings prepared at 3 kHz pulsing conditions. However, the coatings prepared at 5 kHz pulse show non-uniform coarse morphology. All the coatings display low surface roughness i.e. mu m. The hardness result of the coatings was mainly depended on WC incorporation. The Cr-WC coatings show excellent tribological properties, unlike pure Cr coating. After analysis of all the properties, it is observed that Cr-5 g l(-1) WC (3 kHz) shows optimum properties in terms of coating morphology, hardness, and wear behavior.

The pulsed electro-co-deposition process was used on mild steel substrate to develop Ni-W based composite coating which comprises of ZrO2 and TiO2 oxide nanoparticles. In the deposition bath, plating parameters and ZrO2 content were maintained constant, whereas, TiO2 content was varied. Phase constitution, morphology, and chemistry of the coatings were examined by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy respectively. Surface-mechanical properties were evaluated by wear and microhardness test. Potentiodynamic polarization technique and electrochemical impedance spectroscopy were employed to determine the corrosion resistance of the coatings in a 3.5% NaCl solution. In addition, the isothermal oxidation WA was conducted on the coatings at different temperatures (600, 700 and 800 degrees C) to evaluate the oxidation properties. From the experimental results, it got evidenced that microstructure, microhardness, wear, oxidation and corrosion properties of coatings significantly affected by the incorporation of ZrO2 and TiO2 nanoparticles. Under constant ZrO2 content, microhardness, corrosion and wear resistance of the coatings were significantly improved with increasing TiO2 content (0-15 g/L bath). Coatings with TiO2 addition were more beneficial as compared to the Ni-W and Ni-W-ZrO2 coatings. The oxidation resistance of Ni-W coating was improved after the dispersion of ultrafine ZrO2 and TiO2 particles in the matrix. Optimum values of hardness (963 HV0.05), corrosion resistance (R-ct: 6082 +/- 33 Omega.cm(2)) and wear resistance were achieved in the case of NiW-5 g/L ZrO2-15 g/L TiO2 composite coating.