Heat-treatment induced material property variations of Al-coated Mg alloy prepared in aluminum chloride/1-ethyl-3-methylimidazolium chloride ionic liquid

Protective diffusion coatings on magnesium alloys: A review of recent developments

“…This greatly improved the adhesion strength of the coating. Similar results have been obtained by Chuang et al [61]. On the contrary, after heat treatment at 200-300 • C for 6-12 h, a diffusion coating with a tri-layer structure was formed on the AZ91D Mg surface [62,66].…”

“…(a) Typical optical micrographs showing both the Mg2Al3 layer and the Mg17Al12 phase layer before removing the un-reacted Al deposition (b) and after removing the Al deposition [73]. previous work has found that the adhesion strength between such overlay coatings and the substrate Mg alloy is poor, which will strongly restrict their practical applications [61,62]. Therefore, heat treatment of the overlay coatings has been tried to obtain better adhesion, owing to the formation of the metallurgical bonding provided by the diffusion coatings.…”

“…Both layers were passive over a wide potential range, suggesting that either of these intermetallic layers would have significantly better corrosion resistance in an aggressive NaCl environment than AZ91 alloy or pure Mg [65]. Heat treatment of Al coatings deposited in ionic liquid has also been tried [61,62,66]. Adhesion peel-off tests (tape tests) showed that the adhesion between the as-deposited Al coating and the AZ91D substrate was poor [62].…”

“…Based on the above discussion, the structure of the diffusion coatings can be briefly classified as a two-phase structure or layered continuous intermetallic compounds. The Al diffusion coatings are found to reduce the corrosion density of Mg alloys by several to several ten times, and increase the corrosion potential by 30-300 mV depending on the process parameters and the resulting structure [25,[30][31][32]39,40,61,62,65,66,80]. A major difference between the diffusion coatings with different structures lies in the passivation behavior.…”

A study of the deformation and failure mechanisms of protective intermetallic coatings on AZ91 Mg alloys using microcantilever bending

“…However, protective coatings on Mg alloy substrate deposited using these techniques often show poor interfacial adhesion [7,[31][32][33]. This largely restricts their practical application.…”