In this work, the AlSi10Mg alloys with distinct molten pool structures, namely fish-scale and lamellar, were fabricated by using selective laser melting (SLM) technology. The effects of solid ...solution temperature on the microstructural evolution and mechanical properties of the two types of alloys were systematically investigated. The relationship among initial structure, heat treatment and mechanical properties was revealed. The experimental results showed that for the alloy with fish-scale structure, Si diffused more easily after solid solution treatment due to the finer eutectic network, resulting in a larger Si particle size. At 510 °C, the nano Si particles in the fish-scale sample basically disappeared, but a small amount of nano Si particles still existed in the lamellar sample, leading to a bimodal distribution in the Si particle size. Different sizes and distributions of Si particles present different strengthening mechanisms and affect the nucleation and growth of recrystallized grains in the α-Al matrix, leading to significant differences in mechanical properties. The strength of the lamellar sample decreased with increasing the temperature, and the abnormally growth of grains could be found after being treated at 510 °C, resulting in a poor mechanical property. The strength of fish-scale sample first decreased and then increased with the increase of solid solution temperature. When the alloy with fish-scale structure was solid solution treated at 510 °C, Si particles could promote the nucleation of recrystallized grains but hinder their growth, and the ultimate tensile strength decreased from 478.8 MPa of SLMed state to 393.4 MPa, a reduction of 17.8%, while the elongation increased from 7% to 21%, an increase of 300%, showing an excellent overall mechanical property. Therefore, the present study demonstrates that adjusting the SLMed molten pool structure and heat treatment parameters is necessary to obtain a good combination of microstructure and mechanical property.
•SLMed AlSi10Mg alloys with different initial structures have distinct mechanical behaviors after heat treatment.•The size and distribution of silicon particles affect the recrystallisation behavior of α-Al.•The relationship among initial structure, heat treatment and mechanical properties was analysed.•Synergistic optimization of SLM and heat treatment parameters was achieved.
An approach combined the enhanced solution treatment (EST) and the non-isothermal ageing (NIA) treatment was employed on the as-rolled Al-Zn-Mg-Cu alloy. The hardening response is greatly affected by ...the precipitates size distribution and their volume fraction. The supersaturation of the EST alloy is improved since the residual constituent particles are dissolved into the matrix. During heating (100–200 °C), the driving force for precipitation is enhanced and the average precipitate radius is rapidly increased with elevated temperature. Higher volume fraction of precipitates are obtained at the EST-HX conditions (aged at heated X °C), and thus the strength values are superior to those of the traditional HX conditions. Although the coarsening takes place, the average radius of the EST-H210 condition remains smaller than that of the H210 case. And the yield strength of 515 MPa for the EST-H210 condition is still higher compared to that of 474 MPa for the H210 condition. With decreasing temperature (200-140 °C), the secondary precipitation in the EST-CX condition (aged at cooled X °C) is more easily driven by the continuous reduction of solubility. Then the average radii of the EST-CX conditions are lower than those of the CX conditions, while the corresponding volume fractions are higher. Therefore the strength values of the EST-CX conditions increase resume and retain higher. Besides, the peak strength is reached at the EST-C140 condition ahead of time, at which point the tensile strength and yield strength are 589 MPa and 558 MPa, respectively.
•Lower precipitate average radii are obtained for the EST treated alloy during the NIA process.•Higher volume fraction of precipitates are obtained for the EST treated alloy during the NIA process.•Improved strength values are obtained for the EST treated alloy during the NIA process.
•Fatigue properties of 2519A Al alloy were obviously improved after DST.•Increased aspect ratio of grain and PFZ width after DST increased the resistance to crack expansion along GBs.•Bridging effect ...of second phase reduced after DST enhance alloy's fatigue properties.
2519A aluminum alloy thick plates have excellent applications in the military industry due to their superior ballistic resistance and fatigue properties. However, the delamination cracking along the thickness direction of this alloy hinders its further utilization. To address this issue and enhance the fatigue properties of this alloy, the effect of single-stage solid solution treatment (SST) and two-stage solid solution treatment (DST) on the fatigue crack propagation (FCP) behavior in the thickness direction of the alloy was investigated. Compared to the optimum SST, the volume fraction of the secondary phase of the alloy was reduced by 28.6% after DST. The precipitated phases were finer with more uniform distribution, and the volume fraction and number density of the precipitation increased by 47% and 30%, respectively. The DST resulted in a lower fatigue crack growth rate (FCGR) and an increase of 2.92% in the critical stress intensity factor value (ΔKcr). The crack propagation mode of the alloy after SST was inter/transgranular crack propagation, while it was transgranular after DST. The aspect ratio of grain and the number of secondary phases in the alloy decrease after DST. Meanwhile, the grain boundary (GB) precipitation phase spacing, the precipitation-free zone (PFZ) width, and the spacing between the secondary phases increase. These changes result in decreased crack sources in the alloy and reduced the bridging effect of secondary phases on fatigue cracks, thus improving the fatigue performance of the alloy.
In this experiment, Al-Cu-Mg-Ag alloy was used as material and solution temperature was used as variable to investigate its effect on the corrosion properties of the alloy and Hardness test, ...metallographic observation, electrochemical test, intergranular corrosion and exfoliation corrosion test were carried out on three groups of samples. The results show that the intergranular corrosion resistance of the alloy decreases with the increase of solution treatment temperature, and the sample treated at 505 °C has the best performance. This is mainly because grain boundary structure plays a role in increasing PFZ and expanding corrosion channels. The exfoliation corrosion resistance of Al-Cu-Mg-Ag alloy increases first and then decreases, and the sample treated at 515 °C has the best performance. This is due to the dual effects of grain boundary structure and grain morphology. On the one hand, the solution treatment temperature increases, which widens the precipitation-free zone and reduces the electrochemical corrosion resistance of the alloy. On the other hand, the increase of recrystallized grains decreases the cohesion of corrosion products and enhances the electrochemical corrosion resistance of the alloy.
In this study, TiCx-Cu (x = 0.5, 0.6, 0.7) cermets were prepared combined with subsequent solution treatment, and the influences of solution treatment on the microstructures and mechanical properties ...were analyzed. The fracture mechanisms of cermets before and after solution treatment were mainly observed and analyzed. The results show that solution treatment can significantly improve the comprehensive mechanical properties of TiCx-Cu cermets. The fracture toughness KIC of TiC0.5-Cu and TiC0.7-Cu cermets increased by 28% and 11%, respectively. The improvements of the comprehensive properties of TiCx-Cu cermets were benefited by the reduction of the content of hard brittle intermetallic compound Cu4Ti and the refinements of the grain size of Cu.
A comparison routes was designed to investigate the effect of two-steps solution treatment on the austenite reversion and mechanical properties of a 12Cr-10Ni-Mo-Ti cryogenic maraging stainless ...steel. The steel was pre-solution treatment (P-ST) at 750 °C and 950 °C, respectively, followed by identical normal-solution treatment (N-ST) at 750 °C, and then they were aged at 500 °C for austenite reversion. It is found that both routes can refine the martensite matrix, while the P&N-ST at 750 °C can obtain a much finer blocks (2.2 μm) with a higher content of nano-scale retained austenite (19.6 vol%). Dual-phase of martensite and austenite (α'+ γ) can be formed at peak-aging of 1 h, and such accelerated reversion kinetics is related with the two-steps non-diffusion transformation of α'→ γ. High content of retained austenite and much refined martensite substructure can contribute to the reversion process. Besides, first-principles calculations verifies the possible formation of η-Ni3(Ti, Al) from energetics, and the predicated ratio of Al is consistent with the partitioning concentration determined by atom probe tomography. Kinetics simulation further indicates the independent growth behavior of η-precipitates and reversed γ. The precipitation in α' matrix is comparative and regardless of the as-solution annealed microstructure. P-ST at 950 °C & N-ST at 750 °C exhibits a higher yield strength but much lower cryogenic impact toughness, which is mainly related with the less reversed γ formed during aging treatment.
•Two-step solution treatment can effectively refine martensite (α') matrix and obtain nano-scale reversed austenite (γ).•The accelerated reversion kinetics would be related with the two-step non-diffusion transformation of α' → γ.•Both of first-principles calculation and kinetics simulation supports the co-existence of α' + γ + η-Ni3(Ti, Al).•It emphasize the adequate soft reversed austenite is necessary for a more balanced tensile strength-cryogenic toughness.
In order to characterize the effect of solution treatment on the properties of Selective laser melting (SLM) 316L material for nuclear power field, the effects of different solution treatment ...conditions on the microstructure evolution and mechanical properties of 316L material were studied. The results show that 316L material is arc-shaped fish scale structure for as-deposited condition. After solution treatment at 1050 °C and 1150 °C respectively, the material microstructure recrystallizes and the arc boundary between layers disappears. The fracture characteristics is typical ductile fracture characteristic. Compared with temperature of 1050 °C, the material is fully recrystallized at 1150 °C and the microstructure uniformity is improved together with the anisotropy is obviously reduced, meanwhile, the formation of twin structure will be beneficial of improving the mechanical properties which has been demonstrated through metallographic analysis combined with characterization of mechanical performance.
Plasma-liquid systems have attracted increasing attention in recent years, owing to their high potential in material processing and nanoscience, environmental remediation, sterilization, biomedicine, ...and food applications. Due to the multidisciplinary character of this scientific field and due to its broad range of established and promising applications, an updated overview is required, addressing the various applications of plasma-liquid systems till now. In the present review, after a brief historical introduction on this important research field, the authors aimed to bring together a wide range of applications of plasma-liquid systems, including nanomaterial processing, water analytical chemistry, water purification, plasma sterilization, plasma medicine, food preservation and agricultural processing, power transformers for high voltage switching, and polymer solution treatment. Although the general understanding of plasma-liquid interactions and their applications has grown significantly in recent decades, it is aimed here to give an updated overview on the possible applications of plasma-liquid systems. This review can be used as a guide for researchers from different fields to gain insight in the history and state-of-the-art of plasma-liquid interactions and to obtain an overview on the acquired knowledge in this field up to now.
The effects of single-stage solution treatment (SST), enhanced solution treatment (EST), high-temperature pre-precipitation (HTPP) and multi-stage solution treatment (MST) on the microstructure, ...mechanical properties and corrosion resistance of the as-extruded 7055 aluminium alloy (AA7055) helical profile were investigated using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). It was observed that EST and MST could promote the dissolution of the second-phase particles compared with the traditional SST, and the intergranular phases were distinctly discontinuously distributed after HTPP and MST. There was obvious difference in the main texture type and texture strength for the alloy after different solid solution treatments. HTPP could improve the corrosion resistance of the alloy by regulating the intergranular phases, but the mechanical properties were severely weakened. While the good corrosion resistance of the alloy could be obtained by MST without obvious strength loss. As a result, the MST is an ideal solid solution treatment scheme for AA7055.
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