Stress corrosion cracking of rapidly solidified magnesium-aluminum alloys

Characterisation of stress corrosion cracking (SCC) of Mg–Al alloys

“…DHC has been proposed as the mechanism for TGSCC of Mg alloys, although evidence for this is limited [11][12][13][14]. Our numerical model for DHC in Mg predicted crack propagation velocities in the lower range of those reported by previous workers; however, the results were based on speculative values for the H diffusion coefficient and solvus concentration [15].…”

“…Mg alloys with >2% Al concentration typically contain Mg 17 Al 12 (␤-phase) particles, which are highly cathodic relative to the ␣-phase. Consequently, the relationship between Al concentration and SCC susceptibility has previously been associated with the propensity for microgalvanic corrosion of the ␣-phase adjacent to Mg 17 Al 12 precipitates [6,7,14,27,28,30].…”

“…Mg alloys containing Al and Zn are particularly susceptible to SCC [24][25][26][27][28]. The SCC susceptibility of Mg alloys increases with increasing Al concentration [29] despite an increase in the repassivation rate [14]. Mg alloys with >2% Al concentration typically contain Mg 17 Al 12 (␤-phase) particles, which are highly cathodic relative to the ␣-phase.…”

Laser Surface Engineering of Magnesium Alloys: A Review

“…It is well known that accelerated corrosion can occur under stress. 29,37 The corrosion behavior of lasertreated and as-received ACM720 Mg alloy was also investigated by Mondal et al 28 A slight improvement in corrosion resistance for laser-treated samples was observed in this investigation. A discontinuous Mg(OH) 2 layer was observed on the corroded region of base alloy, whereas the Mg(OH) 2 layer was more stable on the laser-melted surface.…”

Fatigue Endurance of Magnesium Alloys

“…The influence of air humidity decreased at higher fatigue crack growth rates at ultrasonic frequencies. Accelerated fatigue crack growth in magnesium alloys at high growth rates was caused by absorbed hydrogen which had weakened bond between atoms (Lynch, 1988) or hydrogen diffusion which caused embrittlement of material (Makar et al, 1993). A significant reduction in lifetimes was found for sand-cast AZ 91E-T6 when specimens were cycled at conventional frequencies (25 Hz) in saltwater.…”