Discontinuous and continuous precipitation characteristics and mechanical properties of a AZ80A magnesium alloy at different aging temperatures

Dissolution of Al2Cu Precipitate in Al2024 Additively Manufactured by Electron Beam Melting

“…This can be compared with the less increase in the mechanical properties of the parts with coarse and thick layers of secondary phases formed at grain boundaries. [ 15–17 ] Dissolution of precipitates in aluminum alloys has also been previously reported. Han et al [ 18 ] and Kim et al [ 19 ] studied the effect of heat treatment on dissolution and melting of Al 2 Cu phase in Al–Si–Cu alloy.…”

Dependence of Tensile Properties and Fracture Behaviors on the Fractions of Continuous and Discontinuous Precipitates in Peak-Aged AZ80A Magnesium Alloy

“…After water cooling, a higher supersaturated vacancy concentration remains. It would accelerate the CP reaction in the following aging process because the CP reaction is controlled by volume diffusion, and a higher vacancy concentration increases the diffusion coefficient [ 24 ]. According to the DP reaction mechanism [ 23 , 28 ], the DP reaction only stops when the Al atoms are exhausted by the CP reaction or when the CP precipitates grow large enough to impede the movement of the DP reaction front.…”

“…This is because the plate phases have a uniform habit plane, effectively impeding non-basal slipping. Moreover, the precipitates in CP regions are much smaller and denser than those in DP regions, which indicates a more substantial hindering effect on dislocations of the precipitates in CP regions than on those in DP regions, according to the Orowan mechanism [ 24 , 36 , 37 ]. Therefore, the precipitation-strengthening of CP regions is much more pronounced than that of DP regions at high temperatures.…”

“…In Mg-Al-based alloys, the β phases in Mg-Al series alloys are precipitated competitively by continuous precipitation (CP) [ 16 , 17 , 18 , 19 ] and discontinuous precipitation (DP) during aging [ 20 , 21 , 22 , 23 ]. Because the continuous precipitates (CPs) induced by CP and the discontinuous precipitates (DPs) conducted by DP have great differences in terms of morphology and distribution, they are different in their precipitation-strengthening effect on the alloys [ 24 ]. Furthermore, their precipitation-strengthening effects are likely to vary with temperature because the deformation mechanisms of magnesium alloys at room temperature are also different from those at high temperatures [ 25 , 26 , 27 ].…”

“…Researchers control the ratio of CP- and DP-region fractions using many methods, including adjusting the aging temperature and time [ 24 , 28 ], grain refinement [ 29 ], micro alloying [ 22 , 30 ], and pre-twinning deformation [ 31 ]. However, other factors affecting the mechanical properties are also induced, such as the sizes and distribution of the precipitates, grain size, new strengthening phases, and twinning.…”