An Al–Li–Mg–Sc alloy with an initial grain size of ∼60 μm was processed by equal-channel angular extrusion (ECAE) at 300 °C up to a total strain of 12. Transmission electron microscopy (TEM) and orientation imaging microscopy (OIM) were employed to establish the mechanism of grain refinement. It was found that new ultrafine grains evolved by a strain-induced continuous process, which is termed continuous dynamic recrystallization (CDRX). At ɛ  ∼ 1, a well-defined subgrain structure had developed. Upon further straining the average mis-orientation of deformation-induced boundaries increased; low-angle boundaries (LAB) gradually converted into true high-angle boundaries (≥15°) (HAB). At ɛ  ∼ 4, arrays of boundaries with low and high angle mis-orientations were observed. At ɛ  ∼ 12, a structure dominated by HAB with an average grain size of ∼0.9 μm was formed. This size is roughly similar to that for subgrains developed at preceding strains. It was shown that CDRX occurs homogeneously; the formation of new grains takes place both along initial boundaries and within interiors of original grains as well.

Continuous dynamic recrystallization in an Al–Li–Mg–Sc alloy during equal-channel angular extrusion

Effect of initial microstructure on the hot compression deformation behavior of a 2219 aluminum alloy

In this study, an age-hardenable 2219 Al–Cu alloy was severely deformed by multidirectional forging (MDF) at 360–510 °C, followed by solution treatment and T8 aging treatment. The evolution of the second-phase Al2Cu particles and the mechanical properties of the T8-aged samples were examined. The results indicated that a higher volume fraction and a more disperse distribution of the fragmented coarse particles were obtained for the sample deformed at low temperatures. The fragmented coarse particles were still difficult to sufficiently dissolve in the Al matrix in the subsequent solution treatment and could act as crack initiation sites, thereby reducing the mechanical properties of the alloy. With increasing the temperature of MDF, the number of coarse particles was gradually decreased, and the particles exhibited a more spheroidized shape after MDF. Correspondingly, more Cu atoms were dissolved in the Al matrix in the subsequent solution treatment, and the uniformity and density of the precipitates after T8 aging were improved. Thus, the mechanical properties of the T8-aged forgings were improved with increasing the temperature of MDF. The optimal mechanical properties were obtained when the deformation temperature was 510 °C, with ultimate tensile strength of 431.2 MPa, yield strength of 341.3 MPa, and elongation of 6.5% at room temperature.

Effects of deformation temperature on second-phase particles and mechanical properties of 2219 Al-Cu alloy

Superplasticity and cavitation in AZ31 Mg alloy at elevated temperatures

An improved process for grain refinement of large 2219 Al alloy rings and its influence on mechanical properties

Superplasticity in a 2219 aluminum alloy

The superplastic properties and microstructure evolution of a 0.15%Zr and 0.7%Cu modified 6061 aluminium alloy were examined in tension at temperatures ranging from 475 to 600°C and strain rates ranging from 7 × 10-6 to 2.8 × 10-2 s-1. The refined microstructure with an average grain size of about 11 μm was produced in thin sheets by a commercially viable thermomechanical process. It was shown that the modified 6061 alloy exhibits a moderate superplastic elongation of 580% in the entirely solid state at 570°C and ϵ = 2.8 × 10-4 s-1. Superior superplastic properties (elongation to failure of 1300% with a corresponding strain rate sensitivity coefficient m of about 0.65) were found at the same strain rate and a temperature of 590°C, which is higher than the incipient melting point of the 6061 alloy (~575°C). The microstructural evolution during superplastic deformation of the 6061 alloy has been studied quantitatively. The presence of a slight amount of liquid phase greatly promotes the superplastic...

D. Gromov

Papers

Superplasticity in a 2219 aluminum alloy

Grain refinement and superplastic behaviour of a modified 6061 aluminium alloy

Effect of liquid phase on superplastic behavior of a modified 6061 aluminum alloy