Dear Zee Shan,

A very brief introduction to Mg alloys is provided by

Materials Science in Design and Engineering, ISBN 978-90-6562-301-0

Information about this textbook can be found on

http://www.vssd.nl/hlf/m017.htm

There is a lot a lot of research on this topic and accessible and you incorporated some of them

https://www.jim.or.jp/journal/e/pdf3/49/05/1071.pdf

https://www.researchgate.net/publication/230681116_Atmospheric_corrosion_of_magnesium_alloys_AZ31_and_AZ61_under_continuous_condensation_conditions

http://www.scientific.net/AMR.239-242.2240

http://www.sciencedirect.com/science/article/pii/S0142112308000431

http://www.sciencedirect.com/science/article/pii/S0142112311001666

http://nopr.niscair.res.in/bitstream/123456789/18365/1/IJCT%2020(3)%20210-216.pdf

http://link.springer.com/article/10.1007/s11223-008-0034-8#page-1

http://www.maneyonline.com/doi/abs/10.1179/174327808X315704

Article Atmospheric corrosion of magnesium alloys AZ31 and AZ61 unde...

Its Because of its application. AZ31 and AZ91 both can be used in various functional application and for past decade in bio-medical application also. They can be used in the implants. There has been a good volume of research you can find under this heading. AZ61  can be used in other applications but not in implants because of its material properties. I think that is the reason why we have much research about the previous one. 

Search for A. Samaniego in Scopus, he´s recently read his phD Thesis on this subjec and he has several articles on AZ31 and AZ61.

You can also find his thesis here:

http://digital.csic.es/bitstream/10261/103674/1/Tesis%20Alejandro%20vers%20def.pdf

It´s in Spanish, but articles in English are included

http://digital.csic.es/bitstream/10261/103674/1/Tesis%20Alejandro%20vers%20def.pdf

Dear Zee,

I am very sorry, but there are many woks published on this topic. You may find it through data-base searchs, for instance using the web of knowledge.

I send you a PDF document just printed from a very quick search on this data base. With the 50 references you will find here you will have a lot of work to search the cross references.

I would like to share with you an useful experience from my own research. At present, once you think in a research topic, whatever it could be, you may be practically sure that at this same moment there will have many people doing research on it. If this is not the case, you risk to have the next Nobel prize.

I hope this will be useful for your future research life.

I am very thankful to all of you for your fruitful remarks over my question.

@P. Van Mourik @Ali Ibrahim Al-Mosawi @Mohd Danish@Blanca Ramirez Barat

and especially to  @Jose San Juan.

I am near to solve out my point of interest about AZ61.

The following article may help you to understand the alloy.

R.C. Zeng*, W. Ke, E.H. Han, Influence of load frequency and ageing heat treatment on fatigue crack propagation rate of as-extruded AZ61 alloy. International Journal of Fatigue, 31(3), 2009: 463–467.

Article Influence of load frequency and ageing heat treatment on fat...