Showing 74 results for Mechanical
Farnoosh Turki, Abdolhossein Jalali Aghchai,
Volume 21, Issue 0 (3-2024)
Abstract
The Directed Energy Deposition (DED) process is very sensitive to thermal environments, tends to produce residual stresses and geometric distortion. It is important to understand the influence of processing parameters on these effects in order to enhance build quality. The objective of this study is to control residual stress and distortion in the DED process by investigating baseplate thickness, number of layers deposited before laser interruption, dwell time, and laser power by a full factorial experiment design. The numerical results were validated by experimental measurement of residual stress using the X-ray diffraction (XRD) technique. The optimized processing conditions resulted in a 43% reduction in residual stress and a 33% decrease in dimensional distortion compared to the baseline setup. Among the four factors, baseplate thickness had the most significant effect, whereas dwell time had the least impact. To the best of the authors’ knowledge, the combined effect of baseplate thickness, dwell time, number of layers deposited before laser interruption, and laser power on residual stress and distortion in DED has not been previously investigated. The findings of this study provide a mathematical basis for future research aimed at optimizing process and material parameters in DED process.
Seyed Farzad Dehghaniyan, Shahriar Sharafi,
Volume 21, Issue 2 (6-2024)
Abstract
Mechanical alloying was employed to synthesize a nanostructured alloy with the chemical formula of (Fe80Ni20)1-xCrx (x= 0, 4). The microstructural and magnetic properties of the samples were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and a vibrating sample magnetometer (VSM). Additionally, theoretical calculations were performed using density functional theory (DFT) under the generalized gradient approximation (GGA). Simulations have demonstrated that an appropriate quantity of chromium (Cr) can dissolve within the BCC-Fe (Ni) structure, resulting in a favorable enhancement of the magnetic moment of the lattice. The XRD results indicated that after 96 hours of milling, Fe (Ni) and Fe (Ni, Cr) with a body-centered cubic (BCC) structure were formed. With increasing milling time, the grain size decreased while the microstrain increased. The saturation magnetization (Ms) of Fe80Ni20 composition increased up to 32 hours of milling, but further milling (up to 96 h) resulted in a decrease in the saturation magnetization However, for the (Fe80Ni20)96Cr4 powders, milling up to 64 h caused a reduction in Ms. The coercivity (Hc) trend was different and increased with longer milling times (up to 96 h) for both compositions.
Padmanaban Ramasamy,
Volume 21, Issue 2 (6-2024)
Abstract
The present investigation delves into the friction stir welding of AA5052 and AZ31B alloys, examining the effects of three distinct parameter configurations. A face-centered central composite design, structured to incorporate full replications for comprehensive and reliable analysis, was employed. A pivotal element of this study is implementing an advanced deep neural network (DNN) model. Characterized by its varied activation functions, structural parameters, and training algorithms, this DNN model was adeptly configured to precisely predict the tensile strength and microhardness of the welded joints. This comprehensive examination also included a quantitative assessment of the parameter effects on joint microstructure and mechanical properties. Flawless welds with exemplary surface characteristics were attained through a meticulously optimized set of parameters: a tool rotation speed set at 825 rpm, a tool traverse speed of 15 mm/min, and a shoulder diameter of 18 mm. During the welding process, the formation of intermetallic compounds, specifically Al12Mg17 and Al3Mg2, was observed. An exceptionally refined grain size of 2.23 µm was observed in the stir zone, contributing to the joint's enhanced tensile strength, measured at 180 MPa. The hardness of the specimen fabricated at the high rotational speed is more elevated due to the brittle intermetallic compounds. The better mechanical properties are related to the reduction and distribution of intermetallic compounds formed in the interface zone.
Ramin Dehghani, Seyed Mojtaba Zebarjad,
Volume 21, Issue 3 (9-2024)
Abstract
Acrylic resins are one of the most important thermoplastic resins used in various industries due to their significant properties. However, they are inherently brittle and addition plasticizers to them is very common. In this study, role of both Polyethylene Glycol (PEG) and Triacetin on the mechanical properties of acrylic resin have been investigated. To do so tensile test, bending and wear tests have been performed. To achieve the optimal mixture of plasticizers, a tensile test has been carried out, and the best percentage of the mixture has been determined. Subsequently, bending and wear tests were conducted, which showed a significant increase in the bending strength of the acrylic resin after the addition of plasticizers. Furthermore, it was found that the abrasion mechanism of the resin was significantly altered compared to its pure state.
Majid Tavoosi,
Volume 21, Issue 3 (9-2024)
Abstract
The present study focuses on the phase and structural features of MnAl intermetallic compound during solid-state synthesis. In this regard, the milling process was done in differentMn50+xAl50-x (0<x<7.5)powder mixtures and the prepared samples were evaluated using X-ray diffractometer, scanning and transmission electron microscopy, differential thermal analysis and vibrating sample magnetometer. The results showed that the τ-MnAl magnetic phase with L10 structure could not be formed during the milling and low temperature annealing. During milling process, Al atoms dissolve in Mn network and a single β-Mn supersaturated solid solution (SSSS) form. The β-Mn (SSSS) phase is unstable and transforms into the icosahedral quasi-crystal as well as γ2-Al8Mn5 and β-Mn stable phases during subsequent annealing.
Tumelo Moloi, Thywill Cephas Dzogbewu, Maina Maringa, Amos Muiruri,
Volume 21, Issue 3 (9-2024)
Abstract
The stability of microstructure at high temperatures is necessary for many applications. This paper presents investigations on the effect of changes in temperature on the microstructures of additively manufactured Ti6Al4V(ELI) alloy, as a prelude to high temperature fatigue testing of the material. In the present study, a Direct Metal Laser Sintering (DMLS) EOSINT M290 was used to additively manufacture test samples. Produced samples were stress relieved and half of these were then annealed at high temperatures. The samples were then heated from room temperature to various temperatures, held there for three hours and thereafter, cooled slowly in the air to room temperature. During tensile testing, the specimens was heated up to the intended test temperature and held there for 30 minutes, and then tensile loads applied to the specimens till fracture. Metallographic samples were then prepared for examination of their microstructures both at the fracture surfaces and away from them. The obtained results showed that changes in temperature do have effects on the microstructure and mechanical properties of Ti6Al4V(ELI) alloy. It is concluded in the paper that changes in temperature will affect the fatigue properties of the alloy.
Zahra Rezayi, Mostafa Mirjalili, Jalil Vahdati Khaki,
Volume 21, Issue 4 (12-2024)
Abstract
Celestite ore, the primary mineral for producing strontium compounds, particularly strontium carbonate, is processed using the black ash method, which involves carbothermic reduction, water leaching, and carbonation. This study aims to investigate the combined effect of mechanical activation and additional graphite on the recovery rate and purity of strontium carbonate. Celestite ore with a strontium sulfate content of 79% was obtained from the Dasht-e-Kavir mine. Acid washing with 10% hydrochloric acid significantly reduced carbonate impurities, resulting in a celestite purity of 96.9%. Mixtures of celestite and graphite with varying amounts of graphite were prepared with and without milling. The mixtures were roasted at 900 °C for 1 hour to form strontium sulfide, followed by hot water leaching. After filtration, sodium carbonate was added to the leachate containing SrS, resulting in the formation and precipitation of white strontium carbonate crystals. The results showed that the addition of graphite increased the recovery rate in unmilled specimens. However, the recovery rate decreased significantly when 1 and 10 hours of milling were applied in the presence of excess graphite. Conversely, in the absence of additional graphite, milling for 1 and 10 hours increased the strontium recovery rate to over 95%. Furthermore, the analysis of strontium carbonate obtained from the sample with the highest recovery rate showed a purity of over 99.9%.
Payam Tayebi, Ramin Hashemi,
Volume 22, Issue 1 (3-2025)
Abstract
This study presents the manufacturing of Al 1050/Mg AZ31B bimetallic sheets using the cool roll bonding process, followed by an investigation of the effect of annealing temperature on mechanical properties and microstructural features. Annealing treatment was performed at 200, 300, and 400 degrees Celsius. Mechanical testing includes tension, micro-hardness, three-point bending, and fracture toughness. Scanning electron microscopy equipped with energy-dispersive X-Ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) were used to investigate the microstructure in the infiltration zone. Mechanical testing shows that increasing the annealing temperature decreases the tensile strength of the two-layer specimens. Micro-hardness, XRD, and SEM-EDX investigations confirm the presence of intermetallic particles in the penetration zone. The Micro- hardness test showed that with the increase of the annealing temperature, the hardness in the penetration zone of Al 1050/Mg AZ31B increases. This increase in micro-hardness result confirms the presence of harder intermetallic phases with increasing annealing temperature in the penetration zone.
Manjunath Vatnalmath, Virupaxi Auradi, Bharath Vedashantha Murthy, Madeva Nagaral, Veeresh Kumar G B, Suresh Shetty, Suresh Shetty,
Volume 22, Issue 2 (6-2025)
Abstract
Dissimilar joints of AA2219 and Ti-6Al-4V alloys are obtained using the vacuum diffusion bonding method. The bonding pressure is controlled in the range of 1-4 MPa by keeping the bonding temperature and holding time constant. The influence of the bonding pressure on the microstructure and mechanical properties of the bonding joints is investigated. The diffusion behaviour across the interface of the bonding joints is increased with the increase in bonding pressure. The interface morphology of the specimen bonded at lower bonding pressures exhibits scraggly voids and cracks. The irregular voids and cracks are squeezed and gradually closed due to the significant increase in the diffusion between Al and Ti. The maximum shear strength of 81 MPa is obtained for the joint made at the bonding pressure of 4 MPa, and a diffusion layer of 0.76 µm is formed at the Ti side interface. The fracture morphology inferred the brittle failure of the bonding joints due to the formation of intermetallic compounds like TiAl, TiAl2, and TiAl3 at the interface of Al and Ti.
Farzaneh Sadat Teimoory Toufal, Alma Kalali, Arvin Attari Navab, Mohadeseh Reyhani, Hamidreza Rezaie, Jafar Javadpour,
Volume 22, Issue 3 (9-2025)
Abstract
Glass ionomer cements (GICs) are widely utilized in clinical restorative dental applications, which suffer from poor mechanical strength. Recent research shows that GIC achieves optimal performance when modified with lower percentage of filler materials, particularly when using nanoparticles, due to the resultant increase in surface area and packing density of the cement. Notably, while some modifications show promise, others fail to deliver improvements in material characteristics. This study addressed a gap in the literature by investigating the impact of acidic/basic additives, such as Diopside (CaMgSi2O6) and Zirconia (ZrO2), on the properties of the cement. The reactivity of zirconia and Diopside differ distinctly from traditional calcium-aluminosilicate glass when exposed to acidic conditions in GICs. Also, to clarify the impact of acidity/basicity on filler reactivity during cement setting, the potential mechanical enhancement effects by using nano-sized particles is limited to submicrons. This research incorporated Diopside at concentrations of 2, 4, and 6 wt.%, and zirconia at 8, 10, and 12 wt.% into a glass powder component. Results demonstrated that adding 8 wt.% Zirconia led to a 49% enhancement in compressive strength, also improve microhardness by 16 wt.%, attributed to its non-reactive nature, minimal dissolution, and high inherent strength of ZrO2. In contrast, Diopside had a detrimental effect due to its basic nature compared to that of glass powder. These findings highlight the potential of zirconia as a valuable reinforcing material for the successful mechanical performance of glass ionomer cements. Conversely, basic fillers like diopside appear unsuitable for achieving improved mechanical performance in these systems.
Yasin Mehdizadeh, Saeed Reza Allahkaram, Mohammad H.mohammad-Ebrahimi, Majid Shamsarjmand,
Volume 22, Issue 4 (12-2025)
Abstract
The present work deals with the corrosion behavior and mechanical properties of a coted AZ31 magnesium alloy through plasma electrolyte oxidation (PEO) coating process in different alkaline electrolytes based on sodium silicate (Si-coating), sodium polyphosphate (P-coating) and sodium aluminate (Al-coating). The scanning electron microscopy (SEM) equipped with the energy dispersive x-ray spectroscopy (EDX) plus x-ray diffraction were recruited to investigate the morphology, chemical composition, and phase structure of coatings, respectively. Microscopic scrutiny revealed that the coating in the phosphate electrolyte was twice as thick and the relative porosity percentage was higher than those formed in the other electrolytes. The phase analysis indicated that the MgO was present as the prevailing phase in the Al-coating and P-coating. However, the dominant phase in the Si-coating was Mg2SiO4. Electrochemical testing was examined in a solution containing 3.5.wt% sodium chloride, showing improvements in corrosion resistance of coated alloys. These investigations confirmed that the corrosion resistance of Si-coating was dramatically higher than others which could be attributed to the presence of the dense and stable Mg2SiO4 phase as well as its relatively low porosity. According to the results of tensile tests, the coated samples had lower tensile strength and elongation than the uncoated one. The tensile strength and elongation diminished upon changing the electrolyte from Al-coating to P-coating, while the yield strength was almost similar. Further analyses indicated that the drop of tensile strength and elongation could be attributed to the presence of cracks and pores in the brittle ceramic PEO coating as stress concentration regions during deformation. Those areas are created due to thermal stress during the coating process and deformation in the elastic stage.
Alireza Hajialimohammadi,
Volume 23, Issue 1 (3-2026)
Abstract
This study successfully synthesized the CoCrFeNiMn high-entropy alloy (HEA) using a two-step powder metallurgy approach: mechanical alloying (MA) followed by spark plasma sintering (SPS). The research investigated the effects of processing parameters, specifically MA duration and SPS temperature, on the alloy's microstructure, densification, and mechanical properties. X-ray diffraction (XRD) analysis after 25 hours of MA (ball-to-powder ratio of 10:1) confirmed the formation of a single-phase face-centered cubic (FCC) solid solution. Scanning electron microscopy (SEM) images revealed significant powder particle refinement, with average particle sizes decreasing from initial micrometers to sub-micrometer ranges. The alloyed powders were then consolidated via SPS at temperatures of 800°C, 900°C, and 1000°C (40 MPa, 10 min in argon). Detailed analysis of the sintered samples showed relative densities ranging from 95.78% to 96.77%, with the highest density (96.77%) achieved at 1000°C. Vickers microhardness measurements exhibited a peak hardness of 446 HV at 900°C, with a decrease to 420 HV at 1000°C, primarily due to grain growth. This research establishes the combined MA and SPS approach as effective for producing high-density, high-hardness HEAs, underscoring the critical role of processing parameters in tailoring their final properties.
Ehsan Bazzaz, Majid Alitavoli, Mehdi Yarmohammad Tooski, Mohammad Mehdi Bazzaz,
Volume 23, Issue 2 (6-2026)
Abstract
Improvement of the mechanical properties of the coated surfaces was the matter of significant researches for a long time. A lot of physical and chemical operations were applied and examined on the coating surfaces successfully, but the effect of the mechanical treatments was not widely investigated. In this paper, the effect of a surface mechanical treatment on the micro coating layer has been studied and investigated. For this purpose, the necessary conditions have been created for implying impact to the coating surface. A setup of gas gun facility with well-designed and prepared projectiles are used to strike the sample surface with different speeds. A significant number of impacts have been inflicted on the test sample of the spade drill insert cutting tool. The consequence of this process is the change in crystal structure of the coating layer, which shows that under the created conditions, the crystal structure was not destroyed and instead getting compacted so that the size of the crystal grains has been reduced and considerably refined. Subsequent studies using electron microscopy have led to the measurement of the average size of the crystalline grains before and after impacts. Obviously, a significant effect has been observed and a meaningful trend has been seen for this change in the form of a linear relationship. The main result is that about 4% reduction in the average grain size happens when the impact speed changes by 10m/s. In this way, the principal basis for the use of this surface treatment in improving the surface properties of the micro coating layers is provided. This leads to the application of such treatments as an industry process for improvement of thin coating mechanical properties.
Sajjad Jameel Ibrahim Al Safawee, Ali Rasooli, Taher Rabizadeh,
Volume 23, Issue 2 (6-2026)
Abstract
There is a global need to develop engineering materials to address the increasing demands in various industries. Spark plasma sintering (SPS) is one of the most distinguished powder metallurgy techniques, offering the opportunity for the fabrication of different types of materials. This work emphasizes optimizations of the important process parameters, including temperature, pressure, and holding time, involved in the SPS of the WC, WC-Co, and WC-Cr, as well as assessing the influence of the content of the Co (6-24 wt.%) and Cr (0.2-1 wt.%) binders on the overall characteristics of the SPS-ed cermets. The results illustrate that the process parameters highly affect the physicomechanical properties of the SPS-ed WC, where the most appropriate conditions from a physicomechanical viewpoint are obtained at a sintering temperature of 1700 °C, a pressure of 80 MPa, and a holding time of 5 min. The included Co binder reduces the optimum temperature and pressure down to 1200 °C and 70 MPa, respectively. The addition of the Co improves the final properties of the WC irrespective of its content. The highest tribomechanical properties are attained when 18 wt. % of Co is added. Similar to that of Co, the incorporation of Cr into the WC increases the tribomechanical performance. In general, the use of Co and Cr metallic binders seems a useful strategy to promote the overall properties of the SPS-ed WC.
