Microstructure Of Alloy Research Articles

Effect of Induction Heating Temperature on the Microstructures and Properties of GH4169 Alloy

Effect of Induction Heating Temperature on the Microstructures and Properties of GH4169 Alloy

Comparing microstructure and mechanical properties of AlSi10 alloy produced by powder bed fusion-laser beam and high pressure die casting

PurposePowder bed fusion-laser beam (PBF-LB) is a rapidly growing manufacturing technology for producing Al-Si alloys. This technology can be used to produce high-pressure die-casting (HPDC) prototypes. The purpose of this paper is to understand the similarities and differences in the microstructures and properties of PBF-LB and HPDC alloys.Design/methodology/approachPBF-LB AlSi10Mg and HPDC AlSi10Mn plates with different thicknesses were manufactured. Iso-thermal heat treatment was conducted on PBF-LB bending plates. A detailed meso-micro-nanostructure analysis was performed. Tensile, bending and microhardness tests were conducted on both alloys.FindingsThe PBF-LB skin was highly textured and softer than its core, opposite to what is observed in the HPDC alloy. Increasing sample thickness increased the bulk strength for the PBF-LB alloy, contrasting with the decrease for the HPDC alloy. In addition, the tolerance to fracture initiation during bending deformation is greater for the HPDC material, probably due to its stronger skin region.Practical implicationsThis knowledge is crucial to understand how geometry of parts may affect the properties of PBF-LB components. In particular, understanding the role of geometry is important when using PBF-LB as a HPDC prototype.Originality/valueThis is the first comprehensive meso-micro-nanostructure comparison of both PBF-LB and HPDC alloys from the millimetre to nanometre scale reported to date that also considers variations in the skin versus core microstructure and mechanical properties.

A novel shell-like structure Zn-5Mn alloy with high strength and high plasticity for degradable oil fracturing tools

Fracturing tools for oil and gas exploitation require high mechanical properties and degradability. Zn alloys are possible to have good mechanical properties and much lower cost than widely used rare-earth Mg alloys, so it is worthy to develop Zn alloys as alternative materials. In this paper, a novel shell-like microstructure of Zn-5Mn alloy has been realized by bottom circulating water cooling. MnZn9 phase appears by the first time in Zn-Mn alloys with Mn < 6.4 wt%. This phase leads to the formation of hard MnZn9/MnZn13 core/shell structure with a high volume fraction of 76 %, dispersed uniformly in soft Zn phase. The alloy has excellent compressive properties without fracture even when stress and strain reach 2776 MPa and 80 %, respectively. Its ultimate uniform compressive stress and strain are 865 MPa and 56 % respectively, beyond widely used dissoluble Mg alloys. Weight loss rate of the Zn-5Mn alloy is two times that of pure Zn, immersed in 3 wt% KCl solution at 93°C. The shell-like Zn-5Mn alloy provides guiding significance of applying Zn alloys in fracturing tools for oil and gas exploitation.

Effect of Ce and Zr on the microstructure and mechanical properties of high-Mg content Al-Mg alloy

Al-7Mg alloy with different Ce and Zr additions were hot and cold rolled to investigate the effects of chemical composition and rolling route on the microstructure and mechanical properties of high-Mg content Al-Mg alloys. The Ce and Zr additions led to the formations of Al11Ce3 and Al3Zr phases in Al-7Mg alloy, and the Zr atoms can be absorbed into the Al11Ce3 phases. The Al11Ce3 phases can be refined by rolling, and the fragmented Al11Ce3 and Al3Zr precipitate phases enhanced the density of dislocations in the studied alloys during rolling. The Al11Ce3 and Al3Zr phases promoted the grain refinement of hot-rolled Al-7Mg-Ce-Zr alloys, but some coarse grains were obtained in the Zr-containing alloys after cold rolling. The rolled alloys with 0.2Ce and 0.25Zr additions own higher second phase and dislocation strengthening effects than the Al-7Mg and Al-7Mg-Ce alloys with the same state, and the yield strengths of the hot-rolled and cold-rolled Al-7Mg-0.2Ce-0.25Zr alloys reach to 242 MPa and 499 MPa, respectively. Furthermore, the ductility of the cold-rolled Al-7Mg-0.2Ce-0.25Zr alloy was improved by its bimodal grain structure.

Effects of YH2 dopant on densification behavior, microstructure and mechanical properties of Ti–6Al–4V alloys

Ti6Al4V-xYH2 (x = 0, 0.1, 0.2, and 0.3 wt%) was produced in this research employing conventional powder metallurgy methods (cold pressing and sintering). The densification behavior, microstructure and mechanical properties of Ti6Al4V alloy caused by the addition of YH2 were systematically studied. The outcomes indicated that the Ti6Al4V containing 0.1 wt% YH2 has received a synergistic increase in ductility and strength (Ultimate tensile strength: 976.4 MPa; Elongation: 9.3 %), which is mainly attributable to the combined effect of grain refinement and purification of impurity oxygen. The study provides an economical approach for employing low-cost, high-oxygen HDH Ti powder to produce high-performance Ti material.

Optimization of friction stir processing parameters to improve mechanical properties and microstructure of Al5083 aluminum alloy reinforced with AlCoCrFeNiSi high-entropy alloy

Abstract This study explores integrating AlCoCrFeNiSi high-entropy alloy (HEA) particles into the Al5083 aluminum alloy matrix via Friction Stir Processing (FSP) to enhance mechanical characteristics. Microstructural analysis reveals a homogeneous distribution and size reduction of HEA particles, contributing to improved structural strength. X-ray diffraction (XRD) examination confirms the formation of solid solution phases in the HEA particles, validating their role in enhancing material properties. Through the utilization of Design of Experiments (DOE) and Response Surface Methodology (RSM), FSP parameters are systematically optimized, enabling precise predictions of mechanical behavior. Multi-response optimization identifies the optimal combination of FSP parameters, resulting in significant enhancements in Ultimate Tensile Strength (UTS) and Hardness, reaching 314 MPa, 42% elongation, and 75 HV, respectively. Scanning Electron Microscopy (SEM) analysis of tensile test specimens elucidates the impact of varied FSP parameters on microstructural features, emphasizing the importance of optimal mixing for improving interfacial bonding and mechanical properties. This study underscores the effectiveness of integrating HEA particles and optimizing FSP parameters to elevate the mechanical properties of Al5083 aluminum alloy, paving the way for tailored composite materials with enhanced performance for specific applications.

Effect of Pr Doping on the Microstructure, Texture, and Magnetostrictive Behavior of Polycrystalline Fe₈₁Al₁₉ Alloys

Effect of Pr Doping on the Microstructure, Texture, and Magnetostrictive Behavior of Polycrystalline Fe₈₁Al₁₉ Alloys

Effect of Equal Channel Angular Pressing on the Microstructure and Shear Strength of an As-Cast Mg-2Si Alloy

Effect of Equal Channel Angular Pressing on the Microstructure and Shear Strength of an As-Cast Mg-2Si Alloy

Microstructure and mechanical property of high-density 7075 Al alloy by compression molding of POM-based feedstock

Metal injection molding of aluminium alloy (MIM-Al) attracts attention, owing to the lightweight, corrosion resistance and good thermal conductivity. However, it is hard to fabricate high-quality MIM-Al due to the hard-to-sinter powder and poor mechanical properties. Here, we report a facile compression molding process for fabricating high-density 7075Al alloy parts using polyformaldehyde (POM)-based feedstock. Pressureless sintering with a high nitrogen flow rate was adopted to promote sintering densification process. The wetting behavior, rheological properties, and morphology of the feedstock were characterized, showcasing the shear-thinning behavior and suitable viscosity for POM-PP-SA binder. Through controlling the compact pressure, mold temperature and holding time, green gear part with good shape retention and dense microstructure was achieved. Influence of process factors and sintering temperature on the microstructure and mechanical properties of 7075Al alloy are investigated. Remarkably, the aluminum alloy components sintered at 610 °C exhibited excellent performance, with a relative density reaching 97.6 % and a tensile strength of 214.8 MPa. This achievement provides a foundation for the industrial application of complex-shaped aluminum alloy components through the compression molding process.

Cooling rate effects on microstructure and diffusion behaviour in Ti65 alloy: Insights from a modified diffusion model

In the continuous cooling process, the growth of the equiaxed α-phase grains in near-α high-temperature titanium alloys is controlled by the diffusion of alloying elements. Establishing a specific connection between the cooling rate and the diffusion behaviour of alloying elements aids in the precise prediction of the evolution of equiaxed α-phase grain size. This study meticulously controlled the cooling rate during the two-phase region annealing treatment of the Ti65 alloy. Using EPMA technology, the diffusion behaviour of solute elements during cooling was accurately characterized. The study found that slowing the cooling rate promotes the coarsening of the lamellar secondary α-phase grains and the growth of the primary equiaxed α-phase grains. At higher annealing temperatures, the growth of equiaxed α-phase grains can occur at faster cooling rates, while coarse lamellar secondary α-phase grains can be retained at slower cooling rates. The diffusion behaviour of solute elements Al, Ta, Mo, and W between the α-phase and transformed β-phase matrix is significantly influenced by the cooling rate, thus they are considered as the controlling elements for the growth of the equiaxed α-phase grains. Based on the diffusion behaviours of these controlling elements, their single-element diffusion models were categorized and integrated for predicting the grain size of the equiaxed α-phase. The predictions from the revised diffusion model show an excellent agreement with the actual results, with an error margin of about 5%.

The influence of pre-strain on the microstructure and recovery properties of cold-rolled TiNiFe alloy tube

Abstract In the present work, the influence of pre-strain on the microstructures and recovery properties of cold-rolled TiNiFe shape memory alloy tube are studied by pre-strain system, phase transformation testing system, electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). It is demonstrated that the pre-strain has significant effects on the recovery properties, transformation temperatures, and microstructures of TiNiFe alloy. With the increase of pre-strain, the kernel average misorientation (KAM) value and the dislocation pill-up increase, causing the recovery rate of the TiNiFe alloy decreases linearly, and maximum of recovery strain is 8%. And the reverse martensite transformation start temperature (TRs) increases from -133°C to -105°C and TRf increases from -124°C to -97°C, as the increase of pre-strain.

Effect of lanthanum oxide on microstructure and mechanical properties of ZK60 magnesium alloy

Different amounts of La2O3 were added to ZK60 alloy to observe the changes in microstructure and mechanical properties of ZK60-XLa2O3 (X = 0, 0.2 wt%, 0.5 wt%) composites. Our findings reveal that within the as-cast ZK60 alloy, the Mg-Zn binary phase is manifested as rod-shaped precipitates, exhibiting a dispersed distribution predominantly along the grain boundary regions. With the increase of La2O3 addition, the rod-like Mg-Zn binary phases are gradually replaced by Mg-Zn-La ternary phases, and these Mg-Zn-La ternary phases are semi-continuously distributed around the grain boundaries. Both ZK602 and ZK605 alloys result in a corresponding improvement in ductility after extrusion. It is noteworthy that the ductility of the as-extruded ZK605 alloy is increased by 59.4% compared to ZK60 at the expense of a reduction of only 3.9% in yield strength. Taken together, the significant increase in ductility of ZK605 is mainly due to the weakening of the basal texture, which is weakened by the redox reaction of La2O3 with the α-Mg matrix, generating the La element. The decrease in yield strength of ZK605 in the extruded state is closely related to the observed grain coarsening phenomenon and the basal texture weakening. At the same time, the ultimate tensile strength of ZK605 shows a slight increase, which is mainly due to the second phase strengthening. The Mg-Zn-La ternary phase exhibits a notably hard character, and it is evident that the distribution of this phase becomes progressively denser as the La2O3 content increases.

Study on solidification organization and phase formation of Fe-6.5wt.%Si high silicon steel by arc melting and heat treatment

Abstract The solidification microstructure and phase formation behavior of Fe-6.5wt.%Si high silicon steel was investigated using arc melting and heat treatment. The alloy phase composition and microstructure were analyzed by XRD and SEM. The magnetic performance was measured at a high- and low-temperature vibration sample magnetometer. The results show that the temperature gradient causes alloy ingot to be roughly divided into three layers. With the decrease in temperature, from the bottom to the top, the phase morphology is fine crystals, columnar internal dendrites, and isoaxial internal dendrites. In the annealing ring ingot, the inner dendrites disappeared, and from the bottom to the top of the sample, the microstructure changed from fine crystal, columnar crystal, and isoaxial crystal, to micro-cracks, which first increased and then reduced. The hysteresis loop curve width of the alloy is narrow, the slope is large, the hysteresis is 0.126 emu/g, and the magnetic utilization after annealing decreases to 0.0667 emu/g, but the coercive force increases to 2.8 Oe/g, and the annealed alloy is more sensitive to the magnetic field and has a high magnetic conductivity coefficient.

Elucidation and verification of cracking behavior in additive manufacturing of alloy 718 based on fractography

This study identified a cracking that occurred continuously in the built direction of an additive manufactured part of alloy 718 by the laser metal deposition method and clarified the cracking behavior. The solidification microstructure of alloy 718 was evaluated by EDS, EPMA, and extraction residue, and it was found that Laves phase, Ti carbides, and Al oxides were formed between the dendrite microstructures. A fracture surface analysis of the cracks revealed that the cracking in the additive manufacturing was hot cracking associated with the liquid film and that the cracking occurred along the grain boundaries. The fracture surface at the beginning of the cracking showed a solidification cracking fracture surface. The experimental investigation for crack propagation during additive manufacturing and the analytical evaluation of the mechanical state around the cracking using thermal elastic-plastic analysis elucidated the cracking behavior during additive manufacturing. If the cracking exists at the fusion boundary, it is suggested that the cracking initiates from the solid-liquid interface towards the solidification direction. Moreover, tensile strain occurred around the cracks during additive manufacturing, particularly the strain was biggest at the crack edge on the fusion boundary. Therefore, the continuous cracking that occurred beyond each layer in the additive manufacturing of alloy 718 in this study can be considered solidification cracking, and its behavior can be further explained as a notch extension cracking that starts from the solidification cracking and continuously occurs in the solid-liquid coexistence temperature region.

Phase composition and microstructure of intermetallic alloys obtained using electron-beam additive manufacturing

The paper investigates the microstructure and phase composition of nickel- and aluminum-based intermetallic alloys obtained using two-wire electron-beam additive manufacturing (EBAM). Relevance of the research is related to the widespread use of intermetallic alloys based on nickel and aluminum (mainly Ni3Al) in various high-temperature applications and the need to use modern production methods when creating machine parts and mechanisms from these alloys. Using EBAM, the billets from intermetallic alloys with different ratios of the content of main components were obtained. Change in concentrations of the basic elements was carried out varying the ratio of feed rates of nickel and aluminum wires during additive manufacturing in the range from 1:1 to 3:1, respectively. The results of microscopic studies of the obtained alloys showed that, regardless of nickel content, the obtained alloys are characterized by a large–crystalline structure with grain sizes in the range of 100 – 300 μm for alloys with a component ratio of 1:1 and 150 – 400 μm for alloys with a component ratio of 2:1 and 3:1. At the same time, the alloy with an equal content of base components is characterized by more uniform grain and microstructure compared to those with high content of Ni. By changing the concentration ratio of the components, phase composition of the resulting billet can be purposefully controlled. In the case of an “equiatomic” content of the base components in the alloy, a NiAl-based compound with a small phase content based on the intermetallides Ni3Al5 and Ni3Al is formed. At high concent­rations of nickel, the intermetallic Ni3Al phase is formed, and at a component ratio of 3:1, structure of the resulting billet consists mainly of Ni3Al phase and the γ solid substitutional solution based on nickel. The paper demonstrates the possibility of direct production of intermetallic alloys with a given phase composition during electron-beam additive manufacturing.

The impact of ultrasonic shock surface treatment technology on the microstructure, mechanical and corrosion properties of FeCrMnCuNiSi high-entropy alloy coating via TIG arc melting

The impact of ultrasonic shock surface treatment technology on the microstructure, mechanical and corrosion properties of FeCrMnCuNiSi high-entropy alloy coating via TIG arc melting

Effect of forming strategies on the microstructure and mechanical properties of thin-walled CuCrZr alloy fabricated by selective laser melting

Thin-walled structures are widely used in industrial fields such as radiators and critical aerospace components due to their advantages in lightweight design. However, traditional manufacturing techniques struggle to meet the high-precision requirements for complex components. Selective Laser Melting (SLM) technology, characterized by high design flexibility and high geometric production freedom, is a promising alternative. This study employs SLM technology to fabricate CuCrZr alloy thin walls and systematically investigates the effects of interlayer rotation angles and placement strategies on the forming quality and mechanical properties of the thin walls produced by SLM. The results indicate that different interlayer rotation angles and placement strategies lead to variations in defect types and shapes. When the interlayer rotation angle is 0° and the specimens are placed perpendicular to the recoater blade, numerous lack-of-fusion (LOF) defects are observed on the specimens. These lack-of-fusion defects are caused by factors such as low scanning line flatness and uneven energy distribution when the interlayer rotation angle is 0°. In contrast to the 0° interlayer rotation angle, the specimens with a 67° rotation angle exhibit significantly more curved columnar grains in the growth direction. The thin-walled specimens with a 67° interlayer rotation angle and placed parallel to the recoater blade show the best mechanical performance, with a maximum tensile strength of 254.19 MPa and an elongation of 48.81 %.

Effect of Laser Powder Bed Fusion Process Parameters on the Microstructures, Mechanical Properties, and Conductivity of CuCrZr Alloy

Effect of Laser Powder Bed Fusion Process Parameters on the Microstructures, Mechanical Properties, and Conductivity of CuCrZr Alloy

An investigation of the microstructure and properties of rolled W-Al2O3 alloy

Pure tungsten and tungsten alloys have been widely used in metallurgy, energy, chemical industry, aerospace, national defense, electronics and other fields. However, there are inevitably some problems in the use of the process, such as high deformation resistance in the forming process prone to crack and fracture, coarse grain and low bending strength problems. Al2O3 particles were added to improve the comprehensive properties of tungsten alloys. In this paper, the W-0.2 wt%Al2O3 tungsten alloy sheets with different thicknesses of 3 mm, 2 mm, and 1 mm were prepared by induction sintering combined with hot rolling. For comparison, the pure tungsten sheet with a thickness of 3 mm was fabricated by the same preparation process. Comparative assessments were made on the microstructure, hardness, and three-point bending properties across types of three thicknesses of W-Al2O3 sheets and pure tungsten sheet with a thickness of 3 mm. The outcomes demonstrate that the microstructure and properties of the tungsten alloy vary considerably depending on the applied rolling degree, which exerts a profound impact on the grain size, morphology, and distribution within the tungsten alloy matrix. Furthermore, the tungsten alloy consistently exhibits significant enhancements over pure tungsten. Characterization of the rolled tungsten alloy revealed that the incorporation of alumina contributes to a reduction in shear band formation and an improvement in texture strength, thereby substantiating its positive impact on the overall mechanical properties of the alloy.

Effect of Pouring Temperature Variation on Cooling Rate, Hardness and Microstructure of Al-Zn in Aircraft Structures

Al-Zn alloys are widely utilized in industries such as automotive, aircraft manufacturing, and advanced military equipment due to their exceptional strength-to-weight ratio. Among various fabrication methods, metal casting is a commonly used technique for producing structural components from these alloys. However, a significant challenge with metal casting is the reduction in mechanical properties compared to the base material before melting. This reduction highlights the need for research to identify the optimal casting conditions, particularly the casting temperature, which plays a crucial role in maintaining and potentially enhancing the material's mechanical properties. Aluminum alloy 7075, known for its high strength, was selected for investigation. According to the Al-Zn phase diagram, the melting point of aluminum alloy 7075, based on the weight percentage specified by the Standard Aluminum Association, is approximately 660°C. Experiments were conducted by varying the pouring temperature during casting in 30°C increments above this melting point. Specifically, the alloy was melted and cast at three different temperatures: 690°C, 720°C, and 750°C. The mold temperature was consistently maintained at 220°C to isolate the effects of the pouring temperature. Results indicate that increasing the casting temperature significantly affects the alloy's microstructure and mechanical properties. As the casting temperature increases, the cooling rate decreases, leading to a finer grain structure. This finer grain size directly contributes to an increase in hardness, suggesting that higher casting temperatures can enhance the mechanical properties of Al-Zn alloys. These findings emphasize the importance of precise control over casting temperatures to optimize the performance characteristics of aluminum alloy 7075 in high-strength applications.