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The present study aims to evaluate plastic deformation's effect by cold-rolling on the precipitation sequence of 2024 aluminum alloy. X-ray diffraction, scanning/transmission electron microscopy, and Vickers microhardness tests have been used to characterize the microstructure and mechanical behavior of the alloys. It was observed that plastic deformation induces changes in the precipitation sequence, which affects the mechanical properties and delays the overaging stage. In the deformed alloy, two hardening peaks were observed. These peaks occurred at 30 min (248 HV ± 5) and 600 min (230 HV ± 2) and were attributed to the θ' and S' phases, respectively. However, in the non-deformed alloy, only a single hardening peak was observed. This peak arose after 300 min aging (208 HV ± 4) and was attributed to the S' phase formation. Thus, the precipitation sequence in the deformed alloy was the following: αSSS–CuMg clusters → GPB-II zones/θ''/θ'/ → S' → S, and for the non-deformed alloy was αSSS–CuMg clusters → GPB-II zones/S'/ → S.

High-frequency induction heating is frequently used to consolidate solid pieces of refractory ceramics. However, this valuable technique has not been deeply evaluated for sample preparation in light metal-based systems as an economical and feasible alternative for rapid sintering routes such as spark plasma sintering. This work deals with the potential use of induction heating to produce highly densified samples with refined microstructure, enhanced mechanical properties, and lower oxygen contamination. Here we demonstrate that induction-sintering can increase the hardness and yield strength in 70 and 80% respectively, compared to a commercial hardened alloy (AA-1350-H19). Theoretical calculations demonstrate that this behavior can be attributed to two main reinforcement mechanisms: dislocations obstruction and grain refinement. The increased mechanical response can be imputed to the effective sub-micron microstructure retention due to its shorter processing time and lower temperature compared to the conventional sintering process. Graphic abstract

According to Lifshitz, Slyozov, and Wagner (LSW) and Trans-Interface Diffusion-Controlled (TICD) theoretical models, this paper reports the microstructure and its coarsening behavior of γ ′ metastable-coherent precipitates in concentration gradient of Ni-13.75Ti (at%)/Ni generated by diffusion couple. The coarsening of precipitates was evaluated in two different Ti contents (R1-11.4Ti (at%) and R2-13Ti (at%)) generated along the concentration gradient and includes average size, size distributions and growth rate. The solvus and metastable-coherent bimodal lines as determined at 850 °C of 9.16 (at%) and 9.92Ti (at%) respectively by scanning electron microscopy. This paper suggests that elastic strains produced by the matrix/precipitate lattice mismatch caused significant deviations between the experimental results and those predicted by the LSW or TIDC theories. Activation energies for TIDC ( Q i ) and LSW ( Q r ) are Q r : 219.69 and 172.61 kJ mol -1 for R1 and R2 regions, respectively, and Q i : 218.46 and 164.56 kJmol -1 for R1 and R2 regions, respectively. A concentration gradient allows the study of various alloys with different concentration and volume-fraction in a single sample.

A medium Mn steel (MMS) was cast by employing a vacuum induction furnace. After that, the steel was hot rolled (HR) in order to achieve a final thickness of 1.4 mm. The microstructure of the sheet was found to be composed of martensite and a little amount of austenite, the Ultimate Tensile Strength (UTS in this processing condition was close to 1600 MPa and a negligible elongation was found. An intercritical annealing (IA) heat treatment was applied to the steel to promote the austenite reversion and increase its amount and stability. Previous thermodynamic simulations and experimental results were used to determine the temperature and time parameters of the IA. After the steel was subjected to this heat treatment, it exhibited an elongation close to 35% and an UTS close to 1100 MPa. Bendability testing was carried out in that condition in order to correlate it with the microstructural changes in the sheet. It was found that the critical bending angle was higher in the IA condition in comparison with the HR state.

The present study, with its practical implications, evaluates the relationship between microstructure and specific wear rate/friction coefficient in A356 alloy and A356/Al 2 O 3 and A356/WC composites after casting and hot-extrusion. The characterization of crystalline phases was carried out using X-ray diffraction, and the microstructure was characterized by scanning electron microscopy. The comprehensive use of rotating (Pin-on-Disk) and linear reciprocating wear testers ensures a thorough understanding of the materials’ specific wear rate and friction coefficient behaviors. The results show a direct relationship between specific wear rate, friction coefficient, microstructure evolution, and hardness in the systems studied after casting and hot extrusion. In addition, the specific wear rate and friction coefficient decrease as the load increases during tests; however, the friction coefficient is more sensitive to hardness values at low loads; at as-cast conditions, this value decreases concerning the reference sample a 13% and 10% for the A356/Al 2 O 3 and A356/WC composites, but at the extruded conditions, increases by 30% and 111%, which is in a direct relationship to values of hardness obtained. Graphical Abstract