Transactions of The Indian Institute of Metals最新文献

This research aimed to achieve three main objectives: studying the effect of milling time on graphite exfoliation, reducing fabrication heating time to prevent aluminum carbide formation, and investigating the impact of (alumina/graphene)/silver on aluminum properties. Four aluminum nanocomposites were produced using cold and hot pressing at 560 °C for 50 min under 1000 MPa. Raman analysis confirmed graphite exfoliation with alumina to graphene after 40 h of milling. The hot-pressed aluminum-5(alumina/graphene)/10 silver exhibited the smallest crystallite size at 79.926 nm and the highest hardness at 61 HV. It also demonstrated the lowest wear rate under different applied loads (45 and 90 N). The coefficient of friction was measured under 90 N, revealing the lowest mean coefficient of friction of 0.5 for aluminum-5(alumina/graphene)/10 silver, attributed to the presence of graphene and silver as solid lubricants. Aluminum/(alumina/graphene) showed superior corrosion resistance in the absence of silver, reducing the corrosion rate from 0.01 mm/year for pure aluminum to 0.0073 mm/year with the addition of 5 (alumina/graphene). The aluminum-5(alumina/graphene)/10 silver recorded a corrosion rate of 0.0114 mm/year.

Aluminum and its diverse alloys are widely utilized in numerous structural applications owing to their distinct characteristics. Furthermore, the mechanical properties of aluminum alloys can be enhanced further through their utilization in the fabrication of metal matrix composites (MMCs). In contemporary times, friction stir processing (FSP) is increasingly employed as a surface modification technique. FSP enhances the surface properties of materials by subjecting them to severe plastic deformation, mixing, and fragmentation of the base material through the spinning action of a rotating tool, coupled with the heat generated by friction. This paper provides a thorough examination of the research conducted in the realm of friction stir welding (FSW) and friction stir processing involving the aluminium alloys with nanoparticles reinforcement and also the strategies involved during reinforcement. It scrutinizes the effects of reinforced nanoparticles on processing parameters, explores the formation of microstructures, and assesses the resulting mechanical properties.

Non-metallic inclusions in steel negatively affect operational processes and mechanical properties based on their morphology, size, physical state and distribution. Inclusion modification is especially important when sulphur levels are high because the sulphides that form can affect the operational process more significantly than the unmodified inclusions themselves. This research is an attempt to examine the impact of cerium addition on tensile and impact toughness properties, grain size, inclusion composition, morphology and fracture surface of microalloyed peritectic grade steel. The impact toughness at − 40 °C significantly increased by 139 and 164% and yield strength improved from 431 to 495 and 483 MPa with the addition of 0.015 and 0.045 wt% cerium, respectively. The improvement in mechanical properties has been attributed to the combined effect of altering the shape and composition of inclusions, refinement in grain size and uniform dispersion of inclusion in matrix.

Aluminum 6061-T6 sheets with a Ti–6Al–4V titanium alloy interlayer were investigated using friction stir welding (FSW) to achieve strong bonding. The influence of welding parameters on welding quality and strength was assessed by varying rotational speeds and traverse speeds, the optimal welding conditions. Welded samples with a cross section of 28 mm and excellent surface smoothness were prepared and analyzed to measure the residual stress using X-ray diffraction (XRD) techniques. This study investigated the effect of tool geometry and type on residual stresses in welded specimens and highlighted the importance of choosing the appropriate tool geometry and type to minimize residual stresses. Furthermore, finite element simulation of the FSW process was conducted using a thermal modeling approach to calculate the heat generated and predict residual stresses using ABAQUS software. Comparison of the residual stress values obtained from numerical simulations with experimental measurements demonstrated the model’s ability to predict residual stresses in FSW adequately. The experimental and numerical results revealed that an increase in rotational speed and tool feeding led to higher stresses in the welded region due to an increased thermal gradient. Examination of the microstructure shows that during the welding process, the weld cross-section has become smaller than the base metal. The ultimate tensile strength and microhardness obtained in optimal conditions were 245 MPa and 108.2 HV, respectively. Examining the fracture surfaces from the tensile tests showed the soft fracture type, which is characterized by the presence of holes and depressions in the three-layer sheet.

This study investigates the influence of annealing temperature and durations on the microstructural, tensile, and fracture toughness properties of Al/Ti laminated metal composite (LMC) in the rolling and transverse directions. Evaluation of the microstructure findings indicated the presence of elongated grains and shear bands in the Al and Ti layers, along with numerous twins in the Ti layer. Specifically, annealing at 550 °C and 600 °C for 6 h initiated recrystallization in the Ti layer. The fracture toughness of the specimens was affected by several factors, including tensile strength, grain size, cutting orientation, formation of intermetallic compounds (IMCs), and recrystallization. A comparison between rolling and transverse directions showed that the grain boundary length was higher in rolling directions, leading to improved resistance to crack propagation. The highest tensile strength (243 MPa) and fracture toughness (35 MPa m0.5) was achieved at 600 °C in the RD.

In this work, CrMnFeCoNi high-entropy alloy coating was successfully prepared on the surface of aluminum alloy by laser cladding. The relationship between the geometrical morphology of the coating cross section and laser process parameters was systematically studied. The influence of line energy and the number of remelting on the morphology of the coating cross section was mainly discussed, and the uniformity of coating elements distribution was regulated by multiple remelting. The coating cross-sectional dimensions, element distribution and hardness values were measured by stereomicroscope, energy-dispersive spectrometer and microhardness tester. The results show that the cladding height of CrMnFeCoNi high-entropy alloy coating increases first and then decreases with the increase of line energy, but the value changes slightly. The cladding width and cladding depth gradually increase with the increase of line energy and remelting times. When the coating is remelted 2 times, there is an incompletely melted island-like CrMnFeCoNi high-entropy alloy powder in the upper left corner of the coating. When remelting 3 times, there is no incompletely melted high-entropy alloy aggregate, and the uniformity of coating is better than that when remelting 2 times. The uniformity of coating composition is the best after 4 remelts, and the hardness of coating reaches 459.67HV_0.2 when the line energy is 0.67 J/mm for 4 remelts.

A high strength Fe–Cr–Co–Ni–Mo stainless maraging steel was realized through additive manufacturing using Laser powder bed fusion (LBPF) technique. As a part of post processing, effect of different heat treatment cycles with and without hot isostatic pressing (HIPping) was studied. The as-printed coupons, subjected to sub-zero treatment and direct aging, were found to meet the specified properties in comparison with other multi-stage heat treatment conditions. Conventional heat treatment cycle exhibited highest strength with fine martensitic structure and HIPed specimens exhibited isotropic properties compared to the un-HIPed specimens. HIPping is found to improve the ductility of material as well, however with a reduced strength by 5–10% owing to grain coarsening in post-HIPping operation.

In this study, a new Al_0.5CrFeMnCo₂ (molar ratio) high entropy alloy was designed. The microstructure and mechanical properties of as-cast and annealed Al_0.5CrFeMnCo₂ high entropy alloy were investigated. FCC+BCC duplex-phase structure is formed in as-cast Al_0.5CrFeMnCo₂ high entropy alloy. Dendritic FCC phase is the predominant constituent phase, and BCC/B2 coherent structure is formed in the inter-dendritic BCC phase. A large number of short-rod small-sized BCC phases are precipitated within FCC dendrites after annealing at 1000 °C for 6 h but unobserved after annealing at 1100 °C and 1200 °C for 6 h. The as-cast Al_0.5CrFeMnCo₂ high entropy alloy exhibits favorable comprehensive mechanical properties, with a compressive fracture strength of 1493 MPa and a plastic strain of 28.3%. After annealing at 1000 °C for 6 h, the compressive fracture strength and plastic strain reached are improved to 1676 MPa and 32.6%, respectively. However, further increase in annealing temperature results in gradual decrease in mechanical properties.

Applying sacrificial anodes to safeguard structures requires better exposure resistance. The effect of adding Ca (x = 0.1, 0.4, 0.7, and 1.0 wt%) and Ti (x = 0.1, 0.2, 0.3, 0.4, and 0.5 wt%) on the microstructure and electrochemical properties of AZ63 magnesium anode alloy has been studied. The corrosion resistance was examined in 3.5 wt% NaCl utilizing electrochemical impedance spectroscopy and potentiodynamic polarization. The microstructure of the base alloy, comprised of primary α-Mg and secondary phase Mg₁₇Al₁₂, extended to grain boundaries. The corrosion resistance was amended by adding the Ti element, which is correlated to the morphology and dispersion of the TiAl₃ phase at the grain boundary. Adding Ca over 0.1 wt% increased the corrosion rate due to the formation of a highly reactive Mg₂Ca phase. It implies that AZ63 alloy anodes are viable.

The article presents a study of the structure and properties of the welding zone and the weld-affected zone (WAZ) of the EP718 nickel alloy joints. The joints are obtained by robotic pulsed gas metal arc welding in argon (GMA welding) with transverse oscillations of the electrode. The studied macrosections of welded joints of high-temperature nickel alloys show an extremely atypical picture of the fine-grained structure of the WAZ with local grain growth regions, comparing to previous experiments using pulsed GMA welding. The welded joints of the EP718 alloy samples of 4 mm thickness obtained by pulsed GMA welding demonstrated the ultimate tensile strength of 1056 MPa. The short-term strength of welded joints of the EP718 alloy 4 mm thickness at 650 °C reached the value of 949 MPa. According to EDXS analysis, particles of the Ti_xN_y type and carbides of the M_xC_y type are distinguished along the boundaries of such areas. These particles are formed in the WAZ zone in the temperature range of 700–1200 °C. A detailed EDXS analysis of WAZ revealed an increased content of molybdenum and sulfur in certain sections with a simultaneous decreased content of niobium and iron, as well as sections with increased (by 50–70% compared to the initial alloy) concentrations of niobium and molybdenum.