AZ91D alloy

Fig. 11 Top weight changes of AZ91D alloy samples vs immersion time in Bmim-NTfr Bottom chemical composition of the sample surface determined via energy dispersive X-ray spectroscopy (EDXS) showing the buildup of a contamination layer. Image adapted from [217]. Image Copyright Wiley-VCH (2007)...

It is common knowledge that magnesium alloys are more resistant to indoor and outdoor atmospheres than is mild steel, and occasionally they are even more resistant than some aluminum alloys. For example, if the concentration of impurity elements is sufficiently low, the AZ91D alloy corrodes much... 

Figure 4-24. Microstructure of die-cast AZ91D Alloy (Song et al., 1999b).

Mathieu S., Kazan J., Rapin C., Steinmetz P. (2000), Corrosion behaviour of die cast and thixocast AZ91D Alloys - the use of sodium linear carboxylates as corrosion inhibitors , in E. Aghion and D. Eliezer (eds). Mg 2000, Proceedings of the Second Israeli International Conference on Mg Science and Technology, Dead Sea, Israel, pp 339-346. 

Potentiodynamie polarization curves of untreated and H-coated AZ91D alloy in 5% NaCl at pH 10.5 solution from CCP to anodic and cathodic directions at scan rate of 1 mVs (A) H-coated, (O) untreated (Nakatsugawa eta/., 1999). 

The influence of mechanochemical effects (MCEs) and creep on corrosion parameters were studied by Bonora et al. (2002). They stated that deformation increases the anodic current densities and shifting the potentials to more active values. It was also shown that the AZ91D alloy has a high corrosion rate in the deformed state than AM50 alloy under stress, while in the nonloading state the corrosion rate was found to be higher for the AM50 alloy. This behavior confirms the MCE theory and the behavior of these alloys at creep. 

Potentiodynamic curves of pure magnesium, and AM50 and AZ91D alloys in 0.05 M sodium tetraborate solution buffered at pH... 

Lafront A-M, Dube D, Tremblay R, Ghali E, Blawert C and Dietzel W (2008), Corrosion resistance of the skin and bulk of die cast and thixocast AZ91D alloy in CD solution using electrochemical techniques , Canadian Metallurgical Quarterly, 47, 459-468. 

Partially protective film plays an important role in the corrosion process of AZ91D alloy [3, 4]. The corrosion process of AZ91D alloy involves three independent surface state variables area fraction of the partially protective film (0) on the alloy surface, the concentration of intermediate species Mg " (Cm), and the continuous changing of potential on P phase (fip). 

From the above theoretical calculation, the EIS of AZ91D alloy in NaCl aqueous solution consists of one capacitive loop in the high-frequency range (double layer), a capacitive loop (surface state variable Cm) and an inductive... 

The EIS of AZ91D alloy at 5 mA anodic current after 6h charging in 1 mol/L NaCI solution. 

During the diffusion process, hydrogen entering the film wonld be ionized, and an MgH2 film formed on the alloy surface. As a result, the corrosion resistance of AZ91D alloy was improved. 

Figure 4.10 described the electronic energy band model for a semiconductor film formed on AZ91D alloy in NaCl aqueous solution. The proposed model has two interfaces (I) substrate alloy/film and (II) film/electrolyte. At interface... 

Therefore, it could be expected that the energy band of the product film on MC AZ91D alloy increased, suggesting that it became difficult for electronic transition from valence band to Fermi level (see Fig. 4.10), which might be the proper explanation for the increasing of corrosion resistance of the product film on MC alloy. 

Left SKPFM image of AZ91D alloy. Right field emission gun scanning electron microscopy (FEG-SEM) image of the same area. The compositions and Volta potentials of points 1-4 are given in Table 7.5. 

S Mathieu, C Rapin, J Kazan, P Steinmetz, Corrosion behaviour of high pressure die-cast and semi-solid cast AZ91D alloys. Corrosion Science, 2002, 44, 2131-2156. 

Typical high-temperature creep of AZ91D alloy In air at applied stress of 50MPa and temperature of 150°C (1) and 175°C (2) (1 - no rupture, 2 - rupture takes place). 

A decrease in creep life of Mg alloys was found with increasing aluminum content from 2.3 to 8.4% in AS21, AM50 and AZ91D alloys [39,40-42]. Under the same stress of 120.5 0.5 MPa, the creep life of these alloys in... 

Cracks filled by phenolic resin in the vicinity of the coated surface of AZ91D alloy after a corrosion creep test in buffer solution (dark area is a-Mg solid solution light area is Mg-i7Ali2 phase). 1 -coating 2 - the crack in coating 3 - the crack in the bulk of the alloy. 

Table 9.3 Creep life of conventional and rheoformed diecast AZ91D alloy in buffer and sodium sulfate solutions at room temperature under the stress of 58 MPa [44]...

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