Ling-ying Ye

Bio: Ling-ying Ye is an academic researcher from Central South University. The author has contributed to research in topics: Alloy & Microstructure. The author has an hindex of 8, co-authored 10 publications receiving 125 citations.

Effects of Yb addition on microstructures and mechanical properties of 2519A aluminum alloy plate

Abstract: The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test, optical microscopy, transmission electron microscopy, scanning electron microscopy and X-ray diffractometer. The results show that addition of 0.17% (mass fraction) Yb increases the density of θ ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ ' phase at 300 °C. Therefore, tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 °C. The results also show that with the addition of 0.30% (mass fraction) Yb, the mechanical properties increase at 300 °C and decrease at room temperature. With Yb additions, the Al 7.4 Cu 9.6 Yb 2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous, thin and spheroidized.

Effect of three-step homogenization on microstructure and properties of 7N01 aluminum alloys

Abstract: The effect of different homogenization treatments on the microstructure and properties of the 7N01 aluminum alloy was investigated using hardness measurements, electrical conductivity measurements, tensile and slow strain rate tests, electron probe microanalysis, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results revealed that three-step homogenization improved the uniformity of Zr distribution by eliminating segregation of the main alloying elements. During the second homogenization step at 350 °C for 10 h, coarse and strip-like equilibrium η phases formed which assisted the nucleation of Al3Zr dispersoids and reduced the width of the precipitate-free zone of A13Zr dispersoids. As a result, coarse recrystallization was greatly reduced after homogenization at 200 °C, 2 h + 350 °C, 10 h + 470 °C, 12 h, which contributed to improving the overall properties of the 7N01 aluminum alloys.

Intermetallic phase evolution of 5059 aluminum alloy during homogenization

Abstract: Intermetallic phase evolution of 5059 aluminum alloy during homogenization was investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The results show that severe dendritic segregation exists in as-cast alloy. The dissolvable intermetallic phases in as-cast alloy consist of Zn- and Cu-rich non-equilibrium β (Al3Mg2) phase, Fe-rich eutectic Al6Mn phase and equilibrium Mg2Si phase. During the homogenization, Zn- and Cu-rich non-equilibrium β (Al3Mg2) phase, Fe-rich eutectic Al6Mn phase and equilibrium Mg2Si gradually dissolve into matrix. Fine dispersed β(Al3Mg2) particles and rod-shaped Al6Mn particles form in the Al matrix after homogenization. The proper homogenization processing is at 450 °C for 24 h, which is consistent with the results of homogenizing kinetic analysis.

Precipitation kinetics of 2519A aluminum alloy based on aging curves and DSC analysis

Abstract: The precipitation kinetics of 2519A aluminum alloy after different cold rolling reductions before aging was investigated by hardness test and differential scanning calorimetry (DSC). The activation energy was calculated according to DSC curves using single heating rate method. The microstructures of as-rolled and peak-aged alloys were observed by transmission electron microscopy (TEM). The result shows that the age hardenability reduces and the activation energy rises with increasing the reduction from 7% to 40%. Nonuniform dislocations are found in as-rolled alloy and inhomogeneous distribution of θ′ phase is revealed in peak-aged alloy when the reduction is 15%. The inhomogeneous distribution of θ′ phase may be related to the age hardenability reducing and activation energy rising.

Grain structure and microtexture evolution during superplastic deformation of 5A90 Al-Li alloy

Abstract: The microstructural evolution of banded 5A90 Al-Li alloy during superplastic deformation at 475 °C with an initial strain rate of 8×10−4 s−1 was studied using EBSD technique. The results showed that, before deformation, the grain shape appeared to be banded, the most grain boundaries belonged to low-angle boundaries, and the initial sheet had a dominate of {110}«112» brasstexture. During deformation, there were grain growth, grain shape change, misorientation increasing and textural weakening. The fraction of high-angle boundaries increased rapidly once the flow stress reached the peak value. Corresponding deformation mechanism for various stages of deformation was suggested. Dislocation activity was the dominant mechanism in the first stage, then dynamic recrystallization occurred, and grain rotation was expected as an accommodation for grain boundary sliding (GBS). At large strains, GBS was the main mechanism.

The microstructure evolution and nucleation mechanisms of dynamic recrystallization in hot-deformed Inconel 625 superalloy

Abstract: Hot compressions tests of Inconel 625 superalloy were conducted using a Gleeble-1500 simulator at different strains between 900 °C and 1200 °C with a strain rate of 01 s −1 Optical microscope, transmission electron microscope and electron backscatter diffraction technique were employed to investigate the microstructure evolution and nucleation mechanisms of dynamic recrystallization It was found that both the size and fraction of dynamically recrystallized grains increase with increasing deformation temperature However, the size of dynamically recrystallized grains almost remains constant with increasing deformation strain The dominant nucleation mechanism of dynamic recrystallization in Inconel 625 superalloy deformed at 1150 °C is the discontinuous dynamic recrystallization, which is characterized by the bulging of the original grain boundaries accompanied with twining The continuous dynamic recrystallization characterized by progressive subgrain rotation occurs simultaneously in dynamic recrystallization process, although it can only be considered as an assistant nucleation mechanism at the early stage of hot deformation

Control of second-phase particles in the Al-Mg-Mn alloy AA 5083

Abstract: The purpose of the present work is to understand the evolution of microstructure and microchemistry during homogenization of the Al-Mg-Mn alloy AA 5083 (Al Mg4.5 Mn0.7) and its influence on down-stream materials properties. The evolution of the particle state during solidification and subsequent homogenization annealing was tracked with a variety of experimental characterization methods and simulated with microchemistry models to analyse the changes in solute level and precipitation. Different homogenization practices were characterized by different sizes, volumes and densities of dispersoids which, in turn, had a clear impact on materials properties, including recrystallization behaviour and flow stress.

Ultrasonic spot welding of carbon fiber reinforced epoxy composites to aluminum: mechanical and electrochemical characterization

Abstract: The mechanical and electrochemical behavior of ultrasonic spot welded hybrid joints, made of AA5754 aluminum and carbon fiber reinforced epoxy with a co-cured thermoplastic surface layer, was studied. The effect of the welding parameters (energy and force) and the thickness of a thermoplastic film, applied as an upper ply in the composite lay-up, on the development of adhesion strength, was investigated. The best mechanical results were obtained when the welding parameters were able to achieve a large bonding area of mechanical interlocking between naked carbon fibers and aluminum and a better load distribution. The electrochemical results excluded the possibility of galvanic corrosion between aluminum and composite adherends thanks to the insulating action provided by the thermoplastic film.

Effect of precipitates on mechanical properties of AA2195

Abstract: Addition of 1–4 wt.% lithium into a conventional Al–Cu–Mg alloy allows lower density and higher mechanical properties, which are attractive for aerospace applications. In this study, fundamental investigations including phase and microstructure evolution, resulting in strengthening, of the AA2195 are conducted to observe a possibility of production with commercial level. Precipitation sequence and kinetics during post-annealing were evaluated with variations of temperature and holding time. Microstructures revealed formation and evolution in representative precipitates including θ (Al 2 Cu), s′ (Al 3 Zr), and T (Al x Li y Cu) series. Aluminum alloys have low hardness, modulus, and strength before aging, but precipitates such as θ′ (Al 2 Cu), s′ (Al 3 Zr), and T 1 (Al 2 LiCu) show enhanced mechanical properties of AA2195 tempered because of their interaction with dislocation. However, longer holding time and higher annealing temperature result in significant decreases in mechanical properties due to the presence of incoherent precipitates ( θ phase) and coarsening of the precipitates via grain-boundary diffusion. In the current study, the tensile strength of 560 MPa was obtained with post-heat treatment without work hardening. This value has never been achieved in other studies. The maximum strength was reported as 500 MPa without a work hardening process.

Hot deformation behavior and 3D processing maps of AA7020 aluminum alloy

Abstract: The hot deformation behavior and microstructural evolution of homogeneous annealed AA7020 aluminum alloy were investigated by isothermal compression tests over the temperatures range of 673–793 K and strain rates range of 0001–1 s−1 According to the experimental results, the flow stress of AA7020 aluminum alloy exhibits a typical dynamic recovery characteristic, and a six-order polynomial strain compensation of Arrhenius-type constitutive equation is developed to describe the hot deformation behavior of the alloy 3D processing maps that taking the effect of strain into account was established to investigate the workability of AA7020 aluminum alloy Based on the 3D processing maps and examination of microstructures, a microstructural characteristic map was established, and it suggests that the recommended processing domains are predicated to be within the temperatures range of 743–793 K and strain rates range of 0004–005 s−1, uniform deformed grains and recovery structures can be found within this domain Microcrack can be found in samples deformed at high strain rates (>01 s−1), and other microstructural characteristics such as partial recrystallization and flow localization can be found in samples deformed within 733−793K/0001–0004 s−1 and 673–733 K/0001–01 s−1, respectively The preponderant soften mechanism is DRV over all the investigated deformation parameter domains, but the role of DRX (includes CDRX and DDRX) is strengthened by deformation at high temperatures with low strain rates, and the maximum volume fraction of recrystallized grains was 387% when it was deformed at 793 K/0001 s−1