Laser Hatch Distance Can Tune Corrosion Behavior and Mechanical Properties While Maintaining the In Vitro Biocompatibility of Additively Manufactured Mg Alloy WE43.

Rare-Earth based magnesium alloys as a potential biomaterial for the future

In binary nickel–silicon alloys the influence of variation in silicon content (0–15%) upon the mechanical properties and resistance to corrosion by hot sulphuric acid is correlated with the structure of the alloys. The influence of ternary additions to alloys containing approximately 10% silicon is discussed, and the beneficial effects of titanium and copper are emphasised. The improvement in mechanical properties and corrosion resistance obtained by the addition of 2–3% titanium is associated with a modification of the alloy structure. The effect of heat treatment on the structure, mechanical properties and corrosion resistance of binary and ternary alloys is discussed. The further improvement in corrosion resistance obtained by additions of titanium + copper (quaternary alloy) and titanium + copper + molybdenum (quinary alloy) is demonstrated. The mechanical properties and corrosion resistance of quinary alloys are discussedin relation to composition and alloy structure. The optimum combination of corrosion resistance and toughness was obtained with a quinary alloy containing 9·25–9·75% Si, 2·5–3·0% Ti, 2·0–3·0% Cu, and 2·75–3·25% Mo.

Influence of hatch distance on processing, microstructure and mechanical properties of AlMgScZr alloy fabricated by laser powder bed fusion

Tuning hatch distance to optimize microstructure and mechanical properties of 2205 duplex stainless steel produced by laser powder bed fusion

Despite their many advantages, the widespread application of magnesium (Mg) alloys is hindered by their high corrosion rates and poor ductility and formability. One effective method for enhancing both the corrosion resistance and mechanical properties, such as ductility, of Mg alloys is through alloying with Rare Earth (RE) elements. These elements have recently garnered significant attention due to their beneficial properties, including an electrode potential similar to that of Mg and their capacity to refine grain size, which contributes to reduced corrosion rates and enhanced alloy strength. This paper explores the common forms of Mg corrosion and elucidates the mechanisms by which RE elements improve corrosion resistance and mechanical behavior in Mg-RE alloys. It also provides a detailed analysis of how each RE element alters the corrosion behavior of Mg-based alloys. By integrating RE elements, it is possible to control corrosion and improve mechanical properties through mechanisms like solid solution strengthening, grain refinement, and the formation and distribution of secondary phases.

Triton X-100 assisted composite of fluorinated graphene and ZIF-8 for epoxy coatings with high corrosion and wear resistance on carbon steel

This paper explores the enhancement of cavitation and corrosion resistance in cast stainless steel through laser beam surface remelting. The influence of laser treatment on material properties was assessed by analyzing the microstructure using optical microscopy, electron microscopy, and X-ray diffraction. Cavitation erosion was evaluated in tap water using an ultrasonic vibration setup, following ASTM G32-2016 standards. Results show that local remelting of the surface with a laser beam causes a reduction in material loss and cavitation erosion rate. Potentiodynamic polarization tests revealed a significant improvement in corrosion resistance, indicated by a reduced corrosion current density in the laser-treated surface. The observed improvements in cavitation and corrosion resistance are attributed to microstructural hardening, characterized by grain refinement and a uniform, homogeneous structure with finely dispersed, small precipitate particles.

Enhancement of the surface properties of selective laser melted maraging steel by large pulsed electron-beam irradiation

Optimization of laser powder bed fusion process to enhance mechanical properties of as-built Ti–6Al–4V samples

Purpose Nowadays, constantly developing technologies make emerging innovations in the engineering field. Al-Si-based materials are the most popular matrices because of their lightweight, making them suitable for aerospace and automobile applications. Design/methodology/approach This research aims to establish the tensile strength and hardness of Al-Si alloy parts manufactured through the Direct Metal Laser Sintering (DMLS) additive manufacturing technique and the effect of certain process parameters, such as laser power, scanning speed, and hatching distance, on the mechanical properties of the resultant component. The Multi-Criteria Decision-Making (MCDM) PROMETHEE method also assesses the tailored mechanical properties for obtaining the best DMLS fabrication process parameters. Findings The better tensile strength of 192 MPa and hardness values of 112 Hv were obtained in the experimental study, depending on the laser speed, hatch distance and scanning rate. The experimental study also provides valuable information about the capability and feasibility of Al-Si alloys for different engineering uses. It is also observed that increased laser speed and hatching distance improve both hardness and tensile strength. The PROMETHEE Model M3, which achieved a net flow of 11.19 and zero entering flow, was favored as the best configuration for its mechanical performance. Originality/value The originality of this research work lies in its focused evaluation of Al-Si alloys manufactured through the DMLS technique, emphasizing the combined influence of process parameters – laser power, scanning speed and hatching distance – on mechanical properties like tensile strength and hardness. By integrating experimental analysis with the MCDM PROMETHEE method, the study offers a unique approach to optimizing DMLS process configurations. This innovative combination of experimental and decision-making techniques provides new insights into tailoring mechanical properties, enhancing the understanding of Al-Si alloys’ potential for advanced aerospace, automotive and engineering applications.

The effect of heat treatment on the microstructure and corrosion behavior of the Mg-10Gd-1Eu-1Zn-0.2Zr alloy (hereafter referred to as Mg-Gd-Eu-Zn-Zr) was investigated in simulated body fluid (SBF), using the commercial WE43 alloy as reference. The as-cast Mg-Gd-Eu-Zn-Zr alloy exhibits a microstructure composed of α-Mg dendritic matrix with intermetallic phases distributed along interdendritic regions. After heat treatment, the microstructure transforms into a coarser dendritic α-Mg matrix accompanied by a reduced fraction of intermetallics. Similar microstructural features have been observed for the cast WE43 alloy. However, heat treatment results in the complete dissolution of the intermetallic phases. Regarding electrochemical response, both alloys show enhanced corrosion resistance after heat treatment. The corrosion response of magnesium is governed by the simultaneous presence of Mg⁺, Mg(OH) 2 , and MgO at the corroding surface, while relaxation processes associated with Mg⁺ and MgO exhibit capacitive behavior, Mg(OH) 2 produces an inductive response. Linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) data reveal an initial increase in polarization resistance ( R p ) for the Mg-Gd-Eu-Zn-Zr alloy during the early stages of immersion, followed by a pronounced decrease. This collapse in R p is attributed mainly to the presence of intermetallics in the eutectic constituents, which compromise the integrity of the corrosion product layer, and the Mg-rich matrix that preferentially dissolves due to galvanic interactions with intermetallics acting as cathodes. The heat-treated Mg-Gd-Eu-Zn-Zr alloy samples exhibit a delayed decrease in R p , resulting from the reduced intermetallic fraction and a more homogeneous distribution of rare-earth elements in solution in the Mg matrix. The reference WE43 alloy samples show a more pronounced improvement in corrosion resistance after heat treatment, owing to the complete dissolution of intermetallic phases and the formation of a more stable and protective surface film. • Microstructure and corrosion behavior of Mg–10Gd–1Eu–1Zn–0.2Zr (wt%) alloy in simulated body fluid (SBF). • Microstructural evolution comparable to that of the commercial WE43 alloy. • Novel approach to the corroding surface of Mg alloys, showing that the surface is mainly composed of three species: Mg⁺, Mg(OH)₂, and MgO. • From a kinetic standpoint, heat treatment enhances corrosion resistance due to a reduced fraction of intermetallics and an increased rare-earth content in the matrix.

The quality of Mg alloys with high specific modulus and specific strength is the lightest in the structural materials. Their density is about 2/3 of aluminium alloys and 1/4 of steels. The weight of whole structural materials is decreased drastically owing to some components or parts produced by Mg alloys. Thus, Mg alloys are widely used in aerospace, weapons, automobile and other fields [1-3]. Meanwhile, Mg alloys has many other advantages, such as excellent electromagnetic shielding performance, shock absorption ability, electric and heat conductivity, etc [4-6]. However, the chemical stability of Mg is very low, and its electrode potential is negative (-2.34V). As a result, the corrosion resistance of Mg alloys is poor in acid and neutral mediums. Furthermore, other properties of Mg alloys, wear resistance, hardness and resistance to high temperature, are also poor. Consequently, the superiority of Mg alloys in the application is restricted to some extent. Nowadays, the researches are concentrated on the improvement of hardness, wear and corrosion resistance of Mg alloys. Energy beam surface modification is an important developing direction, such as plasma micro-arc oxidation [7-11], laser surface treatment [12-16], ion beam surface modification [17-19], etc. A.V. Apelfeld et al [10] have studied oxide protective coatings on the surface of Mg alloys obtained by micro-arc oxidation (MAO). A model of micro-arc coating formation is proposed. For Mg alloys, the structure of MAO coating plays an important role in improvement of corrosion resistance. The research team (Y.M. Wang et al [11]) has investigated that dense oxide coatings formed in alkaline silicate electrolyte with and without titania sol addition are fabricated on AZ91D alloy using micro-arc oxidation. It reveals that the coating thickness decreases from 22μm to 18 μm with increasing concentration of titania sol from 0 to 10 vol. %. Electrochemical tests show that the Ecorr of Mg substrate positively shifts about 300-500 mV and Icorr lowers more than 100 times after micro-arc oxidation. The literature [15] (A.K. Mondal et al) has reported that Mg alloy ACM720 is subjected to laser surface treatment using Nd:YAG laser in argon atmosphere. This treatment is beneficial for enhancing the corrosion and wear resistance of the alloy. The improved corrosion resistance is attributed to the absence of second phase Al2Ca at the rain boundaries, microstructural refinement and extended solid solubility, particularly of Al, in (Mg) matrix owing to rapid solidification. The laser treatment also increases surface hardness two times and reduces the wear rate considerably due to grain refinement.

Improved corrosion resistance and mechanical properties of biodegradable Mg–4Zn–xSr alloys: effects of heat treatment, Sr additions, and multi-directional forging

Titanium alloys are currently used in offshore industries. The titanium alloys used in offshore plants need to have excellent corrosion resistance and mechanical properties because offshore plants are exposed to harsh corrosive environments. At this time, the Ti-6Al-4V ELI alloy is mainly used in offshore plants because it has excellent mechanical properties and corrosion resistance. However, Ti-6Al-4V ELI alloy has the disadvantage of poor formability. To improve this, studies on metastable beta-Titanium alloys with a BCC structure are being actively conducted. In this study, a metastable beta-titanium alloy was fabricated using Mo, which is inexpensive and improves corrosion resistance, and Fe, which improves strength, among the titanium beta stabilizer elements. After the Ti-6Al-4V ELI and Ti-xMo-2Fe alloys solution treatments, electrochemical corrosion experiments were conducted to analyze corrosion characteristics, and mechanical properties were also analyzed through compression tests at room temperature and Vickers hardness measurement. Corrosion properties and the mechanical properties of Ti-xMo-2Fe alloy were considered in connect experiments such as microstructure analysis and hardness measurement. It was confirmed that the corrosion resistance of the Ti-xMo-2Fe alloy was better than that of the Ti-6Al-4V ELI alloy, and it was confirmed that the compressive strength and elongation rate of Ti-xMo-2Fe with its BCC structure get higher than Ti-6Al-4V ELI alloy.

Magnesium (Mg) and its alloys are modern implant materials that are remarkably similar to natural bone. Biomedical researchers have taken notice of its exceptional mechanical properties, biodegradability, and biocompatibility. Despite their excellent physical and mechanical properties, their alloys are restricted to medical applications because of their low corrosion resistance and rapid structural deterioration in physiological environments. The coating is one of the most effective methods to overcome these limitations and improve corrosion resistance. Hydroxyapatite (HA) is a natural inorganic mineral applied as a coating material that shows superior biocompatibility, bioactivity, high osteoconductivity, non-toxicity, non-inflammatory properties, and a slower degradation and corrosion rate when incorporated on an Mg alloy surface. However, HA applications are limited in scope because of their inherent brittleness. Hybrid coatings are frequently used because they can be combined with inorganic and organic coating materials to overcome the limitations of a single-layer coating, such as corrosion resistance, adhesion, and mechanical integrity. Despite layer-by-layer coating, the hybrid coating has excellent mechanical, physiochemical, and biomedical properties. This review summarizes the most recent developments in hybrid coatings with synthetic polymer coatings (PCL/HA, PLA/HA), natural polymer coatings (SF + HA, collagen/HA), and HA/TiO2-based hybrid coatings on biodegradable Mg alloys. In addition, their biocompatibility, corrosion resistance, and mechanical properties have been discussed. Biopolymer-based hybrid coatings could be a promising means to alter the constraints of Mg alloys in biomedical applications.