Editing Titanium (section)

=== Physical properties ===
<section begin=properties/>
As a [[metal]], titanium is recognized for its high [[strength-to-weight ratio]].<ref name=TICE6th>{{cite encyclopedia |title=Titanium |encyclopedia=[[Columbia Encyclopedia]] |edition=6th |date=2000–2006 |publisher=[[Columbia University Press]] |url=https://archive.org/details/columbiaencyclop00laga |location=New York |isbn=978-0-7876-5015-5 |url-access=registration }}</ref> It is a strong metal with low [[density]] that is quite [[ductility|ductile]] (especially in an [[oxygen]]-free environment),<ref name="EBC">{{cite encyclopedia|encyclopedia=Encyclopædia Britannica|title=Titanium|year=2006|url=http://www.britannica.com/eb/article-9072643/titanium|access-date=19 January 2022}}</ref> lustrous, and metallic-white in [[color]].<ref name="Stwertka1998">{{cite book|title=Guide to the Elements|edition=Revised|first=Albert|last=Stwertka|publisher=[[Oxford University Press]]|year=1998|chapter=Titanium|pages= 81–82|isbn=978-0-19-508083-4|chapter-url=https://books.google.com/books?id=K3RWAAAAYAAJ}}</ref> Due to its relatively high melting point (1,668&nbsp;°C or 3,034&nbsp;°F) it has sometimes been described as a [[refractory metals|refractory metal]], but this is not the case.<ref>{{cite web|website=Special Metal Fabrication|url=https://special-metals.co.uk/is-titanium-a-refractory-metal|title=Is Titanium A Refractory Metal|date=3 August 2021 }}</ref> It is [[paramagnetism|paramagnetic]] and has fairly low [[electrical conductivity|electrical]] and [[thermal conductivity]] compared to other metals.<ref name="EBC" /> Titanium is [[superconductivity|superconducting]] when cooled below its critical temperature of 0.49&nbsp;K.<ref>{{Cite journal | doi = 10.1103/PhysRev.92.243| journal = Phys. Rev.| volume = 92| issue = 2| pages = 243–247| year = 1953| title = Superconductivity of Titanium| last1 = Steele | first1 = M. C. | last2 = Hein | first2 = R. A.| bibcode = 1953PhRv...92..243S}}</ref><ref>{{Cite journal | doi = 10.1103/PhysRevB.97.214516| journal = Phys. Rev. B| volume = 97| issue = 21| page = 214516| year = 2018| title = Complete electrodynamics of a BCS superconductor with μeV energy scales: Microwave spectroscopy on titanium at mK temperatures| last1 = Thiemann | first1 = M. |display-authors=etal| arxiv = 1803.02736| bibcode = 2018PhRvB..97u4516T| s2cid = 54891002}}</ref><section end=properties/>

{{anchor|Commercially pure titanium}}
Commercially pure (99.2% pure) [[titanium alloy#Grades of titanium|grades]] of titanium have [[ultimate tensile strength]] of about 434&nbsp;[[megapascal|MPa]] (63,000&nbsp;[[pounds per square inch|psi]]), equal to that of common, low-grade steel alloys, but are less dense. Titanium is 60% denser than aluminium, but more than twice as strong<ref name=Barksdale1968p738/> as the most commonly used [[6061 aluminium alloy|6061-T6 aluminium alloy]]. Certain titanium alloys (e.g., [[Titanium Beta C|Beta C]]) achieve tensile strengths of over 1,400&nbsp;MPa (200,000&nbsp;psi).<ref>{{harvnb|Donachie|1988|loc=Appendix J, Table J.2}}</ref> However, titanium loses strength when heated above {{convert|430|°C|°F}}.<ref name="Barksdale1968p734">{{harvnb|Barksdale|1968|p=734}}</ref>

Titanium is not as hard as some grades of heat-treated steel; it is non-magnetic and a poor conductor of heat and electricity. Machining requires precautions, because the material can [[galling|gall]] unless sharp tools and proper cooling methods are used. Like steel structures, those made from titanium have a [[fatigue limit]] that guarantees longevity in some applications.<ref name="Stwertka1998" />

The metal is a dimorphic [[allotrope]] of a [[hexagonal close packed]] α form that changes into a [[body-centered cubic]] (lattice) β form at {{convert|882|°C|°F}}.<ref name="Barksdale1968p734" /><ref name="schmidt65">{{cite book |last1=Schmidt |first1=F. F. |last2=Wood |first2=R. A. |title=HEAT TREATMENT OF TITANIUM AND TITANIUM ALLOYS BY |date=1965 |publisher=NASA |location=GEORGE C. MARSHALL SPACE FLIGHT CENTER |edition=TECHNICAL MEMORANDUM X-53445 |url=https://ntrs.nasa.gov/api/citations/19660015720/downloads/19660015720.pdf}}</ref> The [[specific heat capacity|specific heat]] of the α form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the β form regardless of temperature.<ref name="Barksdale1968p734" />