Editing Magnesium (section)

== Forms ==
=== Alloys ===
{{Main|Magnesium alloy}}
[[File:Cold rolling of Mg and Mg-1Al-0.1Ca.jpg|thumb|upright=1.4|Magnesium is brittle, and fractures along [[shear band]]s when its thickness is reduced by only 10% by [[cold rolling]] (top). However, after alloying Mg with 1% Al and 0.1% Ca, its thickness could be reduced by 54% using the same process (bottom).]]
As of 2013, consumption of magnesium alloys was less than one million tonnes per year, compared with 50 million tonnes of [[aluminium alloy]]s. Their use has been historically limited by the tendency of Mg alloys to corrode,<ref name="makar13">{{cite journal |doi=10.1179/imr.1993.38.3.138|title=Corrosion of magnesium|year=1993|last1=Makar|first1=G. L.|last2=Kruger|first2=J.|journal=International Materials Reviews|volume=38|issue=3|pages=138–153|bibcode=1993IMRv...38..138M }}</ref> [[Creep (deformation)|creep]] at high temperatures, and combust.<ref name="giz" />

====Corrosion====
In magnesium alloys, the presence of [[iron]], [[nickel]], [[copper]], or [[cobalt]] strongly activates [[corrosion]]. In more than trace amounts, these metals precipitate as [[intermetallic compound]]s, and the precipitate locales function as active [[cathode|cathodic]] sites that reduce water, causing the loss of magnesium.<ref name="giz" /> Controlling the quantity of these metals improves corrosion resistance. Sufficient [[manganese]] overcomes the corrosive effects of iron. This requires precise control over composition, increasing costs.<ref name="giz" /> Adding a cathodic poison captures atomic hydrogen within the structure of a metal. This prevents the formation of free hydrogen gas, an essential factor of corrosive chemical processes. The addition of about one in three hundred parts [[arsenic]] reduces the corrosion rate of magnesium in a salt solution by a factor of nearly ten.<ref name="giz">{{cite web|url=http://www.gizmag.com/stainless-magnesium-corrosion-monash/28856 |title=Stainless magnesium breakthrough bodes well for manufacturing industries |publisher=Gizmag.com |date=29 August 2013|author=Dodson, Brian |access-date=29 August 2013}}</ref><ref>{{Cite journal | last1 = Birbilis | first1 = N. | last2 = Williams | first2 = G. | last3 = Gusieva | first3 = K. | last4 = Samaniego | first4 = A. | last5 = Gibson | first5 = M. A. | last6 = McMurray | first6 = H. N. | doi = 10.1016/j.elecom.2013.07.021 | title = Poisoning the corrosion of magnesium | journal = Electrochemistry Communications | volume = 34 | pages = 295–298 | year = 2013 }}</ref>

====High-temperature creep and flammability====
Magnesium's tendency to [[Creep (deformation)|creep]] (gradually deform) at high temperatures is greatly reduced by alloying with [[zinc]] and [[rare-earth elements]].<ref>{{cite journal |last1=Choudhuri |first1=Deep |last2=Srinivasan |first2=Srivilliputhur G. |last3=Gibson |first3=Mark A. |last4=Zheng |first4=Yufeng |last5=Jaeger |first5=David L. |last6=Fraser |first6=Hamish L. |last7=Banerjee |first7=Rajarshi |title=Exceptional increase in the creep life of magnesium rare-earth alloys due to localized bond stiffening |journal=Nature Communications |date=8 December 2017 |volume=8 |issue=1 |page=2000 |doi=10.1038/s41467-017-02112-z |pmid=29222427 |pmc=5722870 |bibcode=2017NatCo...8.2000C }}</ref> Flammability is significantly reduced by a small amount of [[calcium]] in the alloy.<ref name="giz" /> By using rare-earth elements, it may be possible to manufacture magnesium alloys that are able to not catch fire at higher temperatures compared to magnesium's [[liquidus]] and in some cases potentially pushing it close to magnesium's boiling point.<ref>{{cite journal |last1=Czerwinski |first1=Frank |title=Controlling the ignition and flammability of magnesium for aerospace applications |journal=Corrosion Science |date=September 2014 |volume=86 |pages=1–16 |doi=10.1016/j.corsci.2014.04.047 |bibcode=2014Corro..86....1C }}</ref>

=== Compounds ===
{{Main|Magnesium compounds}}
Magnesium forms a variety of compounds important to industry and biology, including [[magnesium carbonate]], [[magnesium chloride]], [[magnesium citrate]], [[magnesium hydroxide]] (milk of magnesia), [[magnesium oxide]], [[magnesium sulfate]], and magnesium sulfate heptahydrate ([[Epsom salts]]).<ref>{{Cite web |date=2021-03-23 |title=8 Types of magnesium and their benefits |url=https://www.medicalnewstoday.com/articles/types-of-magnesium |access-date=2024-05-04 |website=www.medicalnewstoday.com |language=en}}</ref><ref>{{Cite web |date=2013-10-02 |title=Chemistry of Magnesium (Z=12) |url=https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_and_Websites_(Inorganic_Chemistry)/Descriptive_Chemistry/Elements_Organized_by_Block/1_s-Block_Elements/Group__2_Elements%3A_The_Alkaline_Earth_Metals/Z012_Chemistry_of_Magnesium_(Z12) |access-date=2024-05-04 |website=Chemistry LibreTexts |language=en}}</ref>

As recently as 2020, [[magnesium hydride]] was under investigation as a way to store hydrogen.<ref name=ren14>{{cite journal |last1=Ren |first1=Chai |last2=Fang |first2=Z. Zak |last3=Zhou |first3=Chengshang |last4=Lu |first4=Jun |last5=Ren |first5=Yang |last6=Zhang |first6=Xiaoyi |title=Hydrogen Storage Properties of Magnesium Hydride with V-Based Additives |journal=The Journal of Physical Chemistry C |date=25 September 2014 |volume=118 |issue=38 |pages=21778–21784 |doi=10.1021/jp504766b }}</ref><ref name=baran20>{{cite journal |last1=Baran |first1=Agata |last2=Polański |first2=Marek |title=Magnesium-Based Materials for Hydrogen Storage—A Scope Review |journal=Materials |date=9 September 2020 |volume=13 |issue=18 |pages=3993 |doi=10.3390/ma13183993 |doi-access=free |pmid=32916910 |pmc=7559164 |bibcode=2020Mate...13.3993B }}</ref>

=== Isotopes ===
{{Main|Isotopes of magnesium}}

Magnesium has three stable [[isotope]]s: {{chem|24|Mg}}, {{chem|25|Mg}} and {{chem|26|Mg}}. All are present in significant amounts in nature (see table of isotopes above). About 79% of Mg is {{chem|24|Mg}}. The isotope {{chem|28|Mg}} is radioactive and in the 1950s to 1970s was produced by several nuclear power plants for use in scientific experiments. This isotope has a relatively short half-life (21 hours) and its use was limited by shipping times.

The nuclide {{chem|26|Mg}} has found application in [[isotope|isotopic]] [[geology]], similar to that of aluminium. {{chem|26|Mg}} is a [[radiogenic]] daughter product of [[aluminium-26|{{chem|26|Al}}]], which has a [[half-life]] of 717,000 years. Excessive quantities of stable {{chem|26|Mg}} have been observed in the [[Ca-Al-rich inclusions]] of some [[carbonaceous chondrite]] [[meteorite]]s. This anomalous abundance is attributed to the decay of its parent {{chem|26|Al}} in the inclusions, and researchers conclude that such meteorites were formed in the [[solar nebula]] before the {{chem|26|Al}} had decayed. These are among the oldest objects in the [[Solar System]] and contain preserved information about its early history.

It is conventional to plot {{chem|26|Mg}}/{{chem|24|Mg}} against an Al/Mg ratio. In an [[isochron dating]] plot, the Al/Mg ratio plotted is {{chem|27|Al}}/{{chem|24|Mg}}. The slope of the isochron has no age significance, but indicates the initial {{chem|26|Al}}/{{chem|27|Al}} ratio in the sample at the time when the systems were separated from a common reservoir.