Solution Strengthening Research Articles

Effect of Tempering Temperature on Microstructure and Mechanical Properties of Cr-Ni-Mo-V Rotor Steel

In this paper, we investigated the effects of the matrix and precipitates in Cr-Ni-Mo-V rotor steel on its mechanical properties after water quenching and tempering (450–700 °C). The results indicate that the microstructure and mechanical properties of the steel can be significantly adjusted by changing the tempering temperature. An excellent combination of tensile strength (1028.608 MPa) and elongation (19%) was obtained upon tempering at 650 °C. This is attributed to the martensite lath with a high dislocation density, solid solution strengthening and the strengthening effect of spherical Mo2C and VC particles. At a tempering temperature of 550 °C, the precipitation and development of rod-shaped Fe3Mo3C resulted in a considerable drop in strength. At 650 °C, the dissolution of Fe3Mo3C and dispersion precipitation of Mo2C and VC led to a large rise in strength. At 700 °C, the coarsening of Mo2C and VC, together with the recrystallization of the martensite lath, resulted in a loss in strength. Meanwhile, as the tempering temperature was increased from 450 °C to 700 °C, the tensile fracture characteristics of Cr-Ni-Mo-V rotor steel gradually changed from cleavage fractures to dimple fractures.

Exploring the Effect of Ti on Mechanical and Tribological Properties of an AlCrFe2Ni2Tix High-Entropy Alloy

Low friction and wear constitute a challenge for metallic materials under dry sliding conditions. In the current study, we successfully prepared an AlCrFe2Ni2Tix (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) high-entropy alloy (HEA) consisting of a body-centered cubic (BCC) phase and an AlNi2Ti phase that exhibited an outstanding combination of a compression strength of above 3 GPa and a ductility degree of 26% at room temperature. Under a 20 N load, the dry friction tests showed that AlCrFe2Ni2Ti0.4 HEA had the lowest wear volume (1.498 mm3), with a coefficient of friction of 0.3929. It is related to the volume fraction of AlNi2Ti precipitate increasing with increasing Ti content, thus resulting in better wear resistance. Through the strengthening mechanism analysis, it is crucial to manipulate the composition of the AlNi2Ti precipitate to obtain desirable mechanical properties in the AlCrFe2Ni2Tix HEA. The main mechanism of wear friction is identified as adhesion wear. Therefore, the addition of Ti into AlCrFe2Ni2 HEA can effectively improve its mechanical and wear resistance due to the significant improvement in hardness and its inherent solution strengthening. Our study provides a new strategy for designing new BCC HEAs with a combination of high hardness, yield strength, and excellent wear.

Research Progress of Cu-Ni-Si Series Alloys for Lead Frames

This paper reviews the research progress of Cu-Ni-Si alloy as a lead frame material for ICs. Cu-Ni-Si alloy is considered a strong candidate for lead frame materials due to its excellent mechanical properties and adequate electrical conductivity. The types and properties of Cu-Ni-Si alloys are then discussed in detail, emphasizing strength and conductivity as two key indicators for evaluating the properties of Cu-Ni-Si alloys, as well as the challenges posed by their inverse correlation. The preparation methods of Cu-Ni-Si alloy, including conventional melting, vacuum melting, and jet forming, are also discussed, and the effects of different casting techniques on the alloy’s properties are analyzed. Furthermore, the conductivity and strengthening mechanisms of Cu-Ni-Si alloy, including solid solution strengthening, second phase strengthening, and deformation strengthening, are discussed. The effects of the Ni-Si atomic ratio, trace elements, and rare earth elements on the alloy’s properties are also discussed. Finally, the current research status of Cu-Ni-Si alloy is summarized, and future research directions are identified, including the development of new preparation technologies, establishment of systematic databases, and promotion of green manufacturing and sustainable alloy development.

Unveiling the mechanisms of solid-solution strengthening in Ti alloys with dual-phase structures: an in-depth first-principles investigation

Unveiling the mechanisms of solid-solution strengthening in Ti alloys with dual-phase structures: an in-depth first-principles investigation

Effect of GPa-level pressure on the microstructure and properties of Cu-8Ni-1.8Si alloy

Reducing or completely eliminating the reticular grain boundary phases in alloys is crucial for enhancing the mechanical and electrical properties of Cu-Ni-Si alloys with high nickel and silicon content (Ni + Si > 5wt.%). In this study, we investigated the microstructure, mechanical properties, and electrical conductivity of Cu-8Ni-1.8Si (wt.%) alloy prepared by high-pressure solidification (HPS) and subsequent aging treatment. The interfacial growth stabilizes as the pressure reduces the crystal growth rate, inhibits the diffusion of solute atoms, and increases the solute partition coefficient. The reticulated Ni31Si12 and granular Ni2Si phases disappear under 6GPa pressure, forming a complete Cu (Ni, Si) solid solution. After direct aging treatment, the precipitated phase of the HPS alloy is β-Ni3Si at the early stage of aging. At the peak aging state, β-Ni3Si and δ-Ni2Si phases coexist in the matrix. Additionally, the Avrami equations for the phase transition kinetics of HPS alloys at different aging temperatures were derived from the electrical conductivity data, and the strength contributions from solid solution strengthening and precipitation strengthening were calculated. The alloy aged at 450 °C exhibited the largest volume fraction and the smallest average size of precipitates, resulting in a more pronounced obstruction effect of nano precipitates on dislocation bypassing and demonstrating the best precipitation strengthening effect. At the peak aging states, the alloy's hardness reaches 367.5 HV, and the compressive yield strength reaches 788.2MPa. These results indicate that high pressure is an effective method to improve the solid solution degree of alloying elements and enhance the mechanical properties of Cu-Ni-Si alloys.

Impression creep of a cast Ag-doped AZ91 magnesium alloy

The impact of 0.5 wt% silver (Ag) addition on the creep performance of the as-cast AZ91 Mg alloy was examined through impression creep tests under stresses between 175 and 700 MPa and temperatures in the range 425–525 K. It was found that creep rates were reduced at all temperatures and stress levels following Ag addition. This improvement in creep resistance can be ascribed to a combination of microstructural modification along with reduction and a more homogenous dispersion of the β-Mg17Al12 intermetallic phase. The effect of Ag on solid solution strengthening, the tendency of Ag atoms to abide on the β-Mg17Al12 phase, and the emergence of the thermally stable Mg4Ag particles are regarded as other influential factors. These consequences indicate that Ag is an advantageous alloying element for enhancing high-temperature creep behavior of AZ91 alloy. The creep stress exponents and activation energies acquired for the alloys under investigation were in the range 4.9 to 6.2 and 92 to 125 kJ/mol, respectively. The observed reduction in creep activation energy with rising stress levels indicates the competition between two distinct creep mechanisms, namely dislocation climb governed by pipe and lattice diffusion; the former mechanism dominates at high stress levels, while the latter is predominant at lower stress levels.

Development of Fire Resistance Steel for Structural Applications

Three grades of steel were chosen to evaluate for their fire resistance performance. The steel # 1 (0.18%C-1.37%Mn-0.35%Si-0.12%Cr-0.113%V) is a vanadium micro alloyed steel, while Steel #2 (0.24%C-0.81%Mn-0.19%Si-0.97%Cr-0.2%Mo-0.01%Ti-0.055%Nb) is a titanium and niobium micro-alloyed steel, whereas steel #3 (0.19%C-0.50%Mn-0.19%Si-1.23%Cr-0.40%Mo-0.018%Nb) is a Nb micro alloyed steel. The room temperature and high temperature (@600oC) were evaluated for the fitness for fire resistance steel. It was found that the steel #1 is having the yield ratio (ratio of yield strength at 600oC to room temperature yield strength) of 0.74 while the steel #2 and #3 are having yield ratio of 0.96 and 0.97 respectively. The higher yield ratio of the steel #2 and #3 are due to the presence of Cr, Mo as the solid solution strengthening in addition to the Nb or Nb & Ti micro-alloying. All the three steels with ferrite pearlite microstructure were qualified for the fire resistance norms (2/3=0.67, of the yield strength at 600oC) and however considering the higher carbon equivalent of the steel#2 and #3 only steel#1 can be used for fire resistance structural applications for the replacement of E350 grade.

Advanced phenomenological models guided heat treating processes for LPBF Ti-6Al-4V alloy

Ti-6Al-4V (Ti64) alloy produced by laser powder bed fusion (LPBF) technique consists of an α′-martensite phase, which is usually brittle. Hence, heat treatments are required to promote the α՛→α+β and/or α→β transformations for microstructural optimization to achieve balances between strength and ductility. To guide the selection of heat treatment parameters for the design of LPBF Ti64 microstructures exhibiting optimized strength and ductility, this work explores the suitability of a Johnson-Mehl-Avrami-Kolmogorov (JMAK) and Lifshitz-Slyozov-Wagner (LSW) models. The work showed that the JMAK model can effectively model the heat treatment processes to predict volume fraction of constituent phases in LPBF Ti64. The transformation kinetics was predicted by an extended non-isothermal JMAK model based on differential scanning calorimetry (DSC) experimental data recorded during continuous heating. Moreover, hardness, as a mechanical property index, was measured for a set of specimens. The hardness initially decreased, then remained constant, and finally slightly increased with the increase in β phase fraction and underlying evolution of microstructure. When the β phase fraction was small < 3%, hardness decreased with the continuous coarsening of α lath during heat treatment process. The measured hardness and α lath width for the specimens followed the Hall-Petch relationship. Moreover, the α lath width and heat treatment time at a given temperature were found to undergo the LSW model. Hardness became independent on the β phase fraction of 3-8%, owing to the competition between α lath coarsening and solution strengthening. The hardness slightly increased when the β phase fraction was greater than 8%, because solid solution strengthening of the α phase played a dominant role over the coarsening of α lath width. The experimentally verified JMAK and LSW models are therefore discussed as effective tools to guide the selection of heat treatment parameters for designing the microstructure and hardness/strength of LPBF Ti64 alloy.

High-temperature abrasive wear behaviour of strengthened iron-aluminide laser claddings

Strengthened iron-aluminides (Fe3Al-based) show notable mechanical properties alongside good scratch hardness up to 600 °C. To investigate the influence of strengthening mechanisms for alternative high temperature wear resistant materials, laser metal deposited alloys based on Fe with 30 at.% Al were studied in detail. After cladding the Fe30Al base material and its alloys – with either 5 at.% Si, 5 at.% C or 3 at.% Ti combined with 6 at.% B – thorough investigations by scanning electron microscopy, electron backscatter diffraction, nanoindentation, hot hardness measurements, and high temperature scratch tests were performed.All alloyed Fe3Al-based claddings show increased strength. The highest overall hardness of ~405 HV10 exhibits the carbon-alloyed one containing a high fraction of Fe3AlC0.6 carbides. Contrary, the Ti + B alloyed as well as the Si-alloyed claddings are superior with their scratch hardness (especially at elevated temperatures), through the formation of TiB2 precipitates and pronounced solid solution strengthening, respectively. Wear tests reveal decreasing wear rates with increasing test temperatures (from 20 to 500 to 700 °C) for all alloyed Fe3Al-based claddings due to the formation of abrasive-containing mechanically mixed layers. Contrary, the reference cladding, cobalt-based Stellite 21 exhibits not only a higher wear rate but also increased ones upon increasing the test temperature. Detailed investigations show that the scratch hardness correlates with the wear resistance and that the incorporation of abrasive material into the wear-induced formation of mechanically mixed layers is highly beneficial. Due to this self-protection effect, the promising overall high temperature behaviour, combined with the alloying concept (no Co, Ni, or Cr), these alloyed Fe3Al-based claddings are promising candidates for sustainable wear protection outperforming currently used wear protection solutions.

Синтез самоармованого порошкового матеріалу на основі високоентропійного сплаву

In this work, the formation of a self-reinforced HEA–WC powder material during the mechanical alloying (MA) of a mixture of elemental powders of the W-Fe-Co-Ni system in a planetary ball mill in a gasoline environment was investigated. X-ray diffraction (XRD), microstructural, and energy dispersive spectral (EDS) analysis revealed that after 20 hours of MA of the powders in a carbon-containing medium, a powder material based on a high-entropy alloy was formed. HEA based powder material contains two solid solutions with BCC and FCC crystal structure, as well as a carbide WC phase formed "in-situ" owing to the large negative value of the mixing enthalpy between carbon and tungsten. The “in-situ” formation of WC particles contributes to the enhancement of interfacial bonding with the metal matrix of the HEA. All phase components of the HEA–WC powder material are in the nanostructured state. The particles of the powder material have a close to spherical shape and a bimodal particle size distribution. The powder material consists of fine particles with a size of 1–10 μm and their agglomerates with a size up to 100 μm. The microstructure of the particles consists of the main gray phase of the BCC solid solution, dark spaces of the FCC solid solution and fine WC particles with a size of 0.1 μm to 1 μm evenly distributed in the HEA matrix. High-entropy alloys with the addition of carbon are promising in terms of practical application, because carbon, having a small atomic radius, dissolves as an interstitial element in the crystal lattice of the substitutional solid solutions of the HEA principal elements and, as a result, significantly affects their structure and phase composition, and, therefore, will contribute to the improvement of the mechanical properties of the self-reinforced powder material due to the effects of both solid-solution strengthening by interstitial atoms and the precipitation strengthening by the carbide phase particles.

Unveiling the Origin of the Strengthening Mechanism in a Novel Precious Metal Multi-Principal Elements Alloy.

Precious metal electrical contact materials are pivotal in microelectronic devices due to their excellent chemical stability and electrical properties. Their practical application is hindered by the strength, contact resistance, and high cost. Multi-principal elements alloys (MPEAs) provide the possibility to develop cost-effective materials with enhanced mechanical properties. To address this, a novel precious metal MPEA, PdAgCuAuPtZn alloy, is designed, which exhibits significant solid solution strengthening and aging strengthening effects. The ultimate tensile strength increases from 747MPa in the solution state to 1126MPa in the aged state, while resistivity remains low. This study presents the first systematic investigation into the strengthening mechanisms of precious metal MPEAs using nanoindentation technology. These findings indicate that the aging strengthening of the alloy is attributed to spinodal decomposition (SD) and chemical short-range order (CSRO) in the matrix. Furthermore, the precipitation structure with Cu-rich and Ag-rich phases gradually replaces the matrix, primarily accounting for aging softening. Additionally, it is discovered that precipitation structure can be strengthened by CSRO formed in the Cu-rich phase, thus providing an innovative strengthening in PdAgCuAuPtZn alloy. These results will be beneficial to both deeply understanding the aging behaviors of PdAgCuAuPtZn alloys and designing high-performance precious metal MPEAs.

Effect of Y Addition on Microstructure and Mechanical Properties of CoCrFeNi HEA Coatings by Laser Cladding

In this study, CoCrFeNiYx (x = 0, 0.1, 0.2, 0.3) high entropy alloy (HEA) coatings were produced on Ti6Al4V by laser cladding. The influence of Y on the microstructure and mechanical properties of CoCrFeNi HEA coatings was systematically examined. The analysis uncovered that the coatings primarily consist of three principal phases: α(Ti), Ti2Ni, and TiC. The incorporation of Y led to enhanced lattice distortion, which positively influenced solid solution strengthening. Moreover, grain refinement resulted in a denser microstructure, significantly reducing internal defects and thereby enhancing the coating’s performance. The average microhardness of the CoCrFeNiY0.2 coating was 702.46 HV0.2. The wear rates were 1.16 × 10−3 mm3·N−1·m−1 in air and 3.14 × 10−3 mm3·N−1·m−1 in a neutral solution, which were 27.0% and 30.8% lower than those of the CoCrFeNi coatings, respectively, indicating superior wear resistance. The Y content in the CoCrFeNiY0.3 coating was excessively high, resulting in the formation of Y-rich clusters. The accumulation of these impurities at the grain boundaries led to crack and pore formation, thereby reducing the wear resistance of the coating. Our study demonstrated that laser cladding an optimal amount of Y-doped CoCrFeNi HEA coatings on the Ti6Al4V substrate significantly enhanced the microstructure and mechanical properties of the substrate, particularly its wear resistance in both air and neutral environments, thereby improving the durability and reliability of titanium alloys in practical applications.

Investigation on the Weldability of Developed High‐Strength Hull Structure Steel

The weldability of a developed high‐strength hull structure steel is investigated using a coarse‐grained heat‐affected zone (CGHAZ) thermal simulation and duplex double welding under a heat input of ≈20 kJ cm−1. From the results, the average impact test energy at −50 °C for the simulated CGHAZ samples is 142 J and for samples with V‐notch position 0.5 mm from the fusion line (FL) was 152 J. The impact test energies for the V‐notch position at the FL also show good toughness. The simulated samples and samples from the weld joint are machined into standard sizes to test their tensile strengths, which meet the request high strength. It is concluded that the high strength of the CGHAZ is mainly due to phase transformation and is supplemented by solid solution strengthening. The good low‐temperature toughness is mainly due to the high Ni content. All the results are comparable to the reported mechanical property test results of the weld joint of navy HSLA‐100 steel under a similar heat input. This suggests that the developed high‐strength hull structure steel exhibits satisfactory weldability.

Achieving Strength and Toughness in Dual-Phase Mg-8Li Alloys Through Phase Structure Control and Composite Fracture.

The rising industrial demand for ultra-lightweight materials with exceptional strength and toughness has intensified interest in dual-phase Mg-Li alloys due to their low density and high specific strength. While much of the research on Mg-Li alloys has concentrated on conventional strengthening methods, such as grain refinement and solid-solution strengthening, overcoming the challenge of plastic deformation compatibility between the α- and β-phases remains unresolved. This study focuses on Mg-8Li binary alloy, systematically investigating the impact of rolling deformation temperature and strain on the phase structures. A detailed analysis of fracture behavior reveals a novel brittle-tough composite fracture control strategy that enhances both strength and toughness simultaneously. This work advances the understanding of phase structure control and its role in strengthening and toughening mechanisms, offering critical insights for the development of next-generation dual-phase magnesium alloys.

The Effect of Zirconium on the Microstructure and Properties of Cast AlCoCrFeNi2.1 Eutectic High-Entropy Alloy.

To improve the performance of AlCoCrFeNi2.1 eutectic high-entropy alloys (EHEA) to meet industrial application requirements, ZrxAlCoCrFeNi2.1 high-entropy alloys (x = 0, 0.01, 0.05, 0.1) were synthesized through vacuum induction melting. Their microstructures were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). Additionally, the hardness, low-temperature compressive properties, nanoindentation creep behavior, and corrosion resistance of these alloys were evaluated. The results showed that AlCoCrFeNi2.1 is a eutectic high-entropy alloy composed of FCC and B2 phases, with the FCC phase being the primary phase. The addition of Zr significantly affected the phase stability, promoting the formation of intermetallic compounds such as Ni7Zr2, which acted as a bridge between the FCC and B2 phases. Zr addition enhanced the performance of the alloy through solid-solution and dispersion strengthening. However, as the Zr content increased, Ni gradually precipitated from the B2 phase, leading to a reduction in the fraction of the B2 phase. Consequently, at x = 0.1, the microhardness and compressive strength decreased at room temperature. Furthermore, a higher Zr content reduced the sensitivity of the alloy to loading rate changes during creep. At x = 0.05, the creep exponent exceeded 3, indicating that dislocation creep mechanisms dominated. In the ZrxAlCoCrFeNi2.1 (where x = 0, 0.01, 0.05, 0.1) alloys, when the Zr content is 0.1, the alloy exhibits the lowest self-corrosion current density of 0.034197 μA/cm2 and the highest pitting potential of 323.06 mV, indicating that the alloy has the best corrosion resistance.

Influence of Molybdenum Addition on the Structure, Mechanical Properties, and Cutting Performance of AlTiN Coatings

Though AlTiN coating has been intensively studied, there is still a need to develop AlTiN coating to meet the growing demand of industrial machining. One effective way to improve the performance of AlTiN coating is by adding alloying elements. In this study, AlTiN and AlTiMo coatings were deposited using multi-arc ion plating to investigate the influence of molybdenum addition on the structure, mechanical properties, and cutting performance of AlTiN coatings. Spherical droplets formed on the surfaces of both coatings, with the AlTiMoN coating exhibiting more surface defects than the AlTiN coating. The grazing incidence X-ray diffraction results revealed the formation of an (Al,Ti)N phase formed in the AlTiN and AlTiMoN coatings. Molybdenum doping in the AlTiMoN coating slightly reduced the grain size. Both coatings exhibited excellent adhesion to the substrate. The hardness (H), elastic moduli (E), H/E, and H3/E2 ratios of the AlTiMoN coating were higher than those of the AlTiN coating. The improvement in the mechanical properties was attributed to grain refinement and solution strengthening. Molybdenum doping improved the tribological properties and cutting performance of the AlTiN coatings, which was ascribed to the formation of MoO3 as a solid lubricant. These results show a path to increase the performance of AlTiN coating through molybdenum addition and provide ideas for the application of AlTiMoN coatings for cutting tools.

Improving strength and elongation of laser directed energy deposited Cu-Nb alloy via Ti addition

The Ti element was designed to optimize the Cu/Nb interface structure. The Cu-Nb and Cu-Nb-Ti alloys were successfully prepared by laser directed energy deposition. Results show that the introduction of Ti can change the incoherent Cu/Nb interface into the semi-coherent Cu/β-Cu3Ti/Nb interface. The Cu/Nb interfaces are easily sheared, producing an attractive force on the dislocations, and the dislocations pile up at the incoherent Cu/Nb interfaces. As a consequence, the Cu-Nb deposited alloy exhibits a relatively low total elongation of 7.7 ± 1.1%. Instead, semi-coherent Cu/β-Cu3Ti/Nb interfaces change the movement of dislocations, making it easier for dislocations to transmit across the interface, thus relieving the stress concentration at the interface, which endows the Cu-Nb-Ti deposited alloy the higher total elongation of 13.4 ± 0.2%. In addition, due to the precipitation strengthening and solid solution strengthening, the Cu-Nb-Ti deposited alloy exhibits higher strength of 795 ± 7MPa.

Modeling and analysis of the effects of age hardening, magnesium dissolution, and SiC reinforcement on wear properties in eutectic Al-Si composites using full factorial techniques

Abstract This study aims to explore the effects of age-hardened traces, magnesium (Mg) dissolution, and silicon carbide (SiC) reinforcement on the wear properties of eutectic aluminum-silicon (Al-Si) matrix composites, focusing on optimizing their performance for industrial applications. A systematic investigation was conducted using a full factorial experimental design, with analysis of variance (ANOVA) performed through Minitab software to quantify the individual and interactive effects of these factors on the wear rate and coefficient of friction (COF). The results demonstrated that age-hardened traces significantly enhance wear resistance by promoting the formation of finely dispersed hardening precipitates at moderate ageing temperatures, while over-ageing negatively impacts performance due to precipitate coarsening. SiC reinforcement emerged as a key factor in improving wear resistance, attributed to its high hardness and superior abrasion resistance. The role of Mg dissolution was found to be multifaceted, contributing to solid solution strengthening and grain refinement but also interacting with other variables in complex ways. The study concludes that the optimal combination of 1.5% Mg, 4% SiC, and a peak ageing temperature of 100 °C achieves the best balance between wear resistance and frictional performance. These findings offer valuable insights into the design of high-performance Al-Si composites, highlighting the importance of microstructural control to meet the demands of advanced engineering applications.

High-temperature abrasive wear behaviour of strengthened iron-aluminide laser claddings

Strengthened iron-aluminides (Fe3Al-based) show notable mechanical properties alongside good scratch hardness up to 600 °C. To investigate the influence of strengthening mechanisms for alternative high temperature wear resistant materials, laser metal deposited alloys based on Fe with 30 at.% Al were studied in detail. After cladding the Fe30Al base material and its alloys – with either 5 at.% Si, 5 at.% C or 3 at.% Ti combined with 6 at.% B – thorough investigations by scanning electron microscopy, electron backscatter diffraction, nanoindentation, hot hardness measurements, and high temperature scratch tests were performed.All alloyed Fe3Al-based claddings show increased strength. The highest overall hardness of ~405 HV10 exhibits the carbon-alloyed one containing a high fraction of Fe3AlC0.6 carbides. Contrary, the Ti + B alloyed as well as the Si-alloyed claddings are superior with their scratch hardness (especially at elevated temperatures), through the formation of TiB2 precipitates and pronounced solid solution strengthening, respectively. Wear tests reveal decreasing wear rates with increasing test temperatures (from 20 to 500 to 700 °C) for all alloyed Fe3Al-based claddings due to the formation of abrasive-containing mechanically mixed layers. Contrary, the reference cladding, cobalt-based Stellite 21 exhibits not only a higher wear rate but also increased ones upon increasing the test temperature. Detailed investigations show that the scratch hardness correlates with the wear resistance and that the incorporation of abrasive material into the wear-induced formation of mechanically mixed layers is highly beneficial. Due to this self-protection effect, the promising overall high temperature behaviour, combined with the alloying concept (no Co, Ni, or Cr), these alloyed Fe3Al-based claddings are promising candidates for sustainable wear protection outperforming currently used wear protection solutions.

Surface Cladding of Mild Steel Coated with Ni Containing TiO2 Nanoparticles Using a High-Temperature Arc from TIG Welding

This study explores the use of a high-temperature arc generated during tungsten inert gas (TIG) welding to enhance the mechanical properties of the surface of AISI 1020 steel. An innovative two-step process involves using the high-temperature arc as an energy source to fuse a previously electrodeposited Ni/TiO2 coating to the surface of the substrate. The cladded surface is characterised by a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), an optical microscope (O.M.) equipped with laser-induced breakdown spectroscopy (LIBS), Vicker’s microhardness testing, and pin-on-plate wear testing. The treated surface exhibits a unique amalgamation of hardening mechanisms, including nanoparticle dispersion strengthening, grain size reduction, and solid solution strengthening. The thickness of the electrodeposited layer appears to strongly influence the hardness variation across the width of the treated layer. The hardness of the treated layer when the Ni coating contains 30 nm TiO2 particles was found to be 451 VHN, validating an impressive 2.7-fold increase in material hardness compared to the untreated substrate (165 VHN). Similarly, the treated surface exhibits a twofold improvement in wear resistance (9.0 × 102 µm3/s), making it substantially more durable in abrasive environments than the untreated surface. Microstructural and EDS analysis reveal a significant reduction in grain size and the presence of high concentrations of Ni and TiO2 within the treated region, providing clear evidence for the activation of several strengthening mechanisms.