Microstructure, Mechanical Properties and Corrosion Behaviors of Al–Li–Cu–Mg–Ag–Zn Alloys

Combined with microstructure characterization and properties tests, the effects of Zn contents on the mechanical properties, corrosion behaviors, and microstructural evolution of extruded Al–Li–Cu–Mg–Ag alloys were investigated. The results show that the increase in Zn contents can accelerate hardening kinetics and improve the hardness of peak-aged alloys. The Zn-added alloys present non-recrystallization characteristics combined with partially small recrystallized grains along the grain boundaries, while the T1 phase with finer dimension and higher number density could explain the constantly increasing tensile strength. In addition, increasing Zn contents led to a lower corrosion current density and a shallower maximum intergranular corrosion depth, thus improving the corrosion resistance of the alloys. Zn addition, distributed in the central layer of T1 phases, not only facilitates the precipitation of more T1 phases but also reduces the corrosion potential difference between the T1 phase and the matrix. Therefore, adding 0.57 wt.% Zn to the alloy has an excellent combination of tensile strength and corrosion resistance. The properties induced by Zn under the T8 temper (solid solution treatment + water quenching + 5% pre-strain+ isothermal aging), however, are not as apparent as the T6 temper (solid solution treatment + water quenching + isothermal aging).

Microstructure and Mechanical properties development of ZA27 alloy through heat treatment

In this work, ZA-27 alloy was fabricated and solid solution treatment at 120, 240 and 360 °C for 1 hr., microstructure and physical properties of alloy were studied by X-ray diffraction, scanning electron microscopy. Results observed that the microstructure of ZA-27 alloy manufactured (as-cast) was composed of α, β, η and ε phases, then decomposed to β phase at 360 oC. The heat treatment of ZA-27 alloys influenced on microstructure, decreasing of strength and hardness, but also causes increasing of elongation. The wear rates of changes increase with increasing solid solution treatment

Investigation of the Effect of Heat Treatment on the Microstructures and Mechanical Properties of Al-13Si-5Cu-2Ni Alloy

An experimental investigation was carried out to study the effects of solid solution treatment and aging treatment on the microstructures and mechanical properties of an Al-13Si-5Cu-2Ni alloy. The results show that the size of eutectic silicon decreased with solid solution treatment temperature increasing until 510 °C. Subsequently, the eutectic silicon size continued to increase as the temperature increased to 520 °C. Initially, the acicular eutectic silicon of the as-cast alloy was 10.1 μm in size. After the solid solution treatment at 510 °C, the eutectic silicon size was reduced to 6.5 μm. The θ′ phase is the main strengthening phase in the alloy, therefore, the effect of aging treatment on θ′ phases was explored. As the aging time increased, the diameter, length, and fraction volume of the θ′ phases were found to increase. The main reason for the improved performance of this alloy following heat treatment is the passivation spheroidization of the silicon phase and Orowan strengthening due to the θ′ phases. The optimal tensile strength of an Al-13Si-5Cu-2Ni alloy was obtained after solid solution treatment at 510 °C for 8 h followed by an aging treatment at 165 °C for 8 h. Therefore, this work has great significance for promoting the application of Al alloys at high temperatures.

Influences of the γ′ Phase on the Mechanical Properties of a Nickel-Based Single Crystal Superalloy

After solid solution treatment at 1335°C for 4 hours and cooling to room temperature at different rate, the nickel-based single crystal superalloy were made into three kinds of nickel-based single crystal superalloy materials containing different size γ′ phases, respectively. The tensile test of I-shaped specimens was carried out at 980°C, and their effect of γ′ phase microstructure on the tensile properties was studied. The results show that the yielding strength of the material air-cooled to room temperature was lower than that with cooling rate at 0.15°C/s, but both of them were lower than the yielding strength of original material. Little difference was found on the elastic modulus of I-shaped specimens made of three kinds of materials. When the cubic degree of the γ′ phase is higher and the size is larger, the tensile properties of the material is better, which can be attributed to the larger size and narrower channel of the matrix phase that lead to higher dislocation resistance.

Mechanical Properties Enhancement of Al-Si-Cu-Fe Alloy Through Aging Treatment Variations

Al-Si alloys are being widely used as main engine components replacing iron in several parts in the automotive industry. Some of its mechanical properties were a reference in its alloy utilization. In this research, the heat treatment carried out on the specimen included solid solution treatment and the artificial aging process for aluminium alloys. Test pieces were heated on the furnace with a solid solution treatment process at 540 ° C with holding time around 5 hours and quenched at 60 °C with water quenchant, followed by 3 different aging treatment which included single-stage aging, artificial aging with pre-aged, and double stage aging. Tests carried out by hardness test, tensile strength test, impact test, metallographic and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) observations. The results of this research showed the differences in phase constituent and morphology microconstituents due to variations of aging. The difference of each treatment could be seen in the morphology of the precipitate that is dispersed, rounded and needle-like shaped, this phase can influence the mechanical properties of Al-Si-Cu alloys. The results of mechanical testing show the highest hardness was obtained by double stage aging treatment 161.27 HRB. The highest tensile strength occurs in specimens with a single-stage aging treatment of 202.56 MPa. The highest impact resistance occurred in samples with the pre-aging treatment of 18.6 J.