An investigation into the dissolution characteristics of γ precipitates in Mg-3Al-Zn alloy

Abstract

In non-equilibrium conditions, the coring phenomena may occur in the α-Mg solid solution and γ-Mg 17 Al 12 phase forms in the microstructure of AZ magnesium alloy series. This eutectic phase may introduce detrimental effect on workability of wrought alloys. In the present work, the dissolution characteristics of γ phase have been investigated in AZ31 wrought magnesium alloy. Considering the eutectic temperature of AZ31 alloy, the homogenization treatment was executed in temperature range of 300-437 °C (i.e., somewhat below eutectic melting temperature of γ precipitate) and 437-500 °C (i.e., higher eutectic melting temperature of γ precipitate) for different durations. A thorough microstructural investigation and also thermodynamic calculations were executed. The results indicated that the dissolution rate of γ phase is very low even at temperatures just below the eutectic point of the alloy, whereas it dramatically increases at temperatures higher than eutectic point. Moreover, it is suggested that partial melting of γ phase due to eutectic melting reaction (α+γ→L) may lead to reduced formability.

Investigation into the Extrudability of a New Mg-Al-Zn-RE Alloy with Large Amounts of Alloying Elements

“…To push the temperature limit upwards, the as-cast alloy was solid-solution-treated at 693 K (420 C) for 24 h, following by water quenching, in order to dissolve second-phase particles, such as Mg17Al12 that has an incipient melting point of 710 K (437 °C) [40]. The solution treatment was also intended to homogenize the as-cast microstructure and improve its extrudability.…”

“…11c). After the solid-solution treatment at 693 K (420 °C) for 24 h, the Mg17Al12 phase with a melting point of 701 K (437 °C) [40] disappeared due to its dissolution into the Mg matrix. The volume fraction of second-phase particles decreased significantly to 2.1% (Fig.…”

Recent research advances on corrosion mechanism and protection, and novel coating materials of magnesium alloys: a review

“…However, under actual solidification conditions, such as AZ91 magnesium alloy, a dissociated eutectic structure or a non-equilibrium eutectic structure will be formed. 86 For AZ31, Al is completely dissolved in α-Mg without the formation of β-phase. 87 Since excessive Al may cause neurotoxicity, which is closely related to the occurrence of Alzheimer's disease, Mg–Al medical magnesium alloys are gradually being replaced by other series of alloys.…”

Investigation of The Effect of Semi-Solid Temperatures and Holding Times at Isothermal Range On Microstructure of AZ31 Mg Alloy

“…AZ31 alaşımında düşük ikincil alaşım elementleri oranına rağmen, tane sınırlarında ve tane içinde ayrılan ötektiğin oluşabileceği Mohammadi, J. Ve arkadaşları ile Monas, A. ve arkadaşlarının çalışmalarında [18,21] daha önce ayrıca raporlanmıştır.…”