Editing Group 4 element (section)

==Applications==
<!--Separation of hafnium and zirconium becomes very important in the nuclear power industry, since zirconium is a good fuel-rod cladding metal, with the desirable properties of a very low neutron capture cross-section and good chemical stability at high temperatures. However, because of hafnium's neutron-absorbing properties, hafnium impurities in zirconium would cause it to be far less useful for nuclear reactor applications. Thus a nearly complete separation of zirconium and hafnium is necessary for their use in nuclear power. The production of hafnium free zirconium is the main source for hafnium. The separation is difficult.<ref name="Stwertka">{{cite book|last=Stwertka|first=Albert|title=A Guide to the Elements|url=https://archive.org/details/guidetoelements00stwe|url-access=registration|publisher=Oxford University Press|year=1996|pages=[https://archive.org/details/guidetoelements00stwe/page/117 117–119]| isbn = 0-19-508083-1}}</ref>-->
Titanium metal and its alloys have a wide range of applications, where the corrosion resistance, the heat stability and the low density (light weight) are of benefit. The foremost use of corrosion-resistant hafnium and zirconium has been in nuclear reactors. Zirconium has a very low and hafnium has a high [[neutron capture|thermal neutron-capture cross-section]]. Therefore, zirconium (mostly as [[zircaloy]]) is used as [[Cladding (metalworking)|cladding]] of [[fuel rod]]s in [[nuclear reactor]]s,<ref name="ASTM">{{cite book|url = https://books.google.com/books?id=dI_LssydVeYC|title = ASTM Manual on Zirconium and Hafnium|first = J. H.|last = Schemel|publisher = ASTM International|year = 1977|isbn = 978-0-8031-0505-8|pages = 1–5}}</ref> while hafnium is used in [[control rod]]s for [[nuclear reactor]]s, because each hafnium atom can absorb multiple neutrons.<ref name="Hend" >{{cite web |title = Hafnium|first = James B. |last = Hedrick |url = http://minerals.er.usgs.gov/minerals/pubs/commodity/zirconium/731798.pdf|publisher = United States Geological Survey|access-date = 2008-09-10}}</ref><ref>{{cite journal|title = Reactive Metals. Zirconium, Hafnium, and Titanium|first = Donald|last = Spink|journal = Industrial and Engineering Chemistry|year = 1961|volume = 53|issue = 2|pages = 97–104|doi = 10.1021/ie50614a019}}</ref>

Smaller amounts of hafnium<ref name="hightemp">{{cite web|url = http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/sub_3/images/pdfs/016.pdf|title = Niobium alloys and high Temperature Applications|first = John|last = Hebda|publisher = CBMM|year = 2001|access-date = 2008-09-04|url-status = dead|archive-url = https://web.archive.org/web/20081217080513/http://www.cbmm.com.br/portug/sources/techlib/science_techno/table_content/sub_3/images/pdfs/016.pdf|archive-date = 2008-12-17}}</ref> and zirconium are used in super alloys to improve the properties of those alloys.<ref name="Super">{{cite book|url = https://books.google.com/books?id=vjCJ5pI1QpkC&pg=PA235|title = Superalloys| first = Matthew J.|last = Donachie| publisher = ASTM International|year = 2002|isbn = 978-0-87170-749-9|pages = 235–236}}</ref>