Editing Refractory metals (section)

===Physical===
{| class="wikitable centered" style="text-align:center"
|+Properties of the refractory metals| Properties of the refractory metals
! Name
! [[Niobium]]
! [[Molybdenum]]
! [[Tantalum]]
! [[Tungsten]]
! [[Rhenium]] 
|-
! Period
! 5
! 5
! 6
! 6
! 6
|- 
! Group
! 5
! 6
! 5
! 6
! 7
|- 
| style="background-color:lightgrey; text-align:left" | [[Melting point]] K<ref group=prop name=melt>Consensus values taken from [[melting points of the elements (data page)|melting points of the elements]] with multiple references there.</ref>
| 2750 || 2896 || 3290 || 3695 || 3459
|- 
| style="background-color:lightgrey; text-align:left" | [[Boiling point]] K<ref group=prop name=boil>Consensus values taken from [[boiling points of the elements (data page)|boiling points of the elements]] with multiple references there. Tungsten has a particularly wide band of discrepancy, with two primary sources reporting 5555 °C.</ref>
| 5017 || 4912 || 5731 || 6203 || 5869
|- 
| style="background-color:lightgrey; text-align:left" | [[Melting point]] °C<ref group=prop name=melt/>
| 2477 || 2623 || 3017 || 3422 || 3186
|- 
| style="background-color:lightgrey; text-align:left" | [[Boiling point]] °C<ref group=prop name=boil/>
| 4744 || 4639 || 5458 || 5930 || 5596
|- 
| style="background-color:lightgrey; text-align:left" | [[Density]] g·cm<sup>−3</sup><ref group=prop name=dense>Consensus values taken from [[densities of the elements (data page)|densities of the elements]] with multiple references there.</ref>
| 8.57 || 10.28 || 16.69 || 19.25 || 21.02
|- 
| style="background-color:lightgrey; text-align:left" | [[Young's modulus]] GPa
| 105 || 329 || 186 || 411 || 463
|-
| style="background-color:lightgrey; text-align:left" | [[Vickers hardness]] MPa
| 1320 || 1530 || 873 || 3430 || 2450
|}

{{Reflist|group=prop}}

Refractory metals have high melting points, with tungsten and rhenium the highest of all elements, and the others' melting points exceeded only by [[osmium]] and [[iridium]], and the sublimation of [[carbon]]. These high melting points define most of their applications. All the metals are [[body-centered cubic]] except rhenium which is [[Close-packing of spheres|hexagonal close-packed]]. The physical properties of the refractory elements vary significantly because they are members of different [[Group (periodic table)|groups of the periodic table]].<ref name="Lipi">{{cite journal | doi = 10.1007/BF00775076 | title = Investigation of the temperature dependence of the hardness of molybdenum in the range of 20–2500°C | year = 1963 | last1 = Borisenko | first1 = V. A. | journal = Soviet Powder Metallurgy and Metal Ceramics | volume = 1 | pages = 182–186 | issue = 3| s2cid = 137686216 }}</ref><ref name="Habishi">{{cite journal | first = Habashi | last = Fathi | year = 2001 | title = Historical Introduction to Refractory Metals | journal = Mineral Processing and Extractive Metallurgy Review | volume = 22 | issue = 1 | pages = 25–53 | doi = 10.1080/08827509808962488| bibcode = 2001MPEMR..22...25H | s2cid = 100370649 }}</ref> The hardness, high melting and boiling points, and high [[Enthalpy of atomization|enthalpies of atomization]] of these metals arise from the partial occupation of the outer [[d subshell]], allowing the d electrons to participate in metallic bonding. This gives stiff, highly stable bonds to neighboring atoms and a [[body-centered cubic]] crystal structure that resists deformation. Moving to the right in the periodic table, more d electrons increase this effect, but as the d subshell fills they are pulled by the higher nuclear charge into the atom's inert [[Core electron|core]], reducing their ability to delocalize to form bonds with neighbors. These opposing effects result in groups 5 through 7 exhibiting the most refractory properties.<ref name="G&E">{{Greenwood&Earnshaw2nd|pages=978, 1005, 1043}}</ref>

[[Creep (deformation)|Creep]] resistance is a key property of the refractory metals. In metals, the starting of creep correlates with the melting point of the material; the creep in aluminium alloys starts at 200&nbsp;°C, while for refractory metals temperatures above 1500&nbsp;°C are necessary. This resistance against deformation at high temperatures makes the refractory metals suitable against strong forces at high temperature, for example in [[jet engines]], or tools used during [[forging]].<ref>{{cite book | chapter-url =https://books.google.com/books?id=LRK59pGvDDwC&pg=PA86 | pages = 86–93 | isbn =978-7-302-12535-8| title =Manufacturing engineering and technology| publisher = Pearson Prentice Hall | first1 =Kalpakjian| last1 = Schmid | chapter = Creep | year =2006}}</ref><ref>{{cite book | chapter-url =https://books.google.com/books?id=w29kfcFkwOMC&pg=PA81 | pages = 81–93 | isbn =978-0-8247-7726-5| title =Thermal fatigue of metals| publisher = CRC Press | year = 1991 | first1 = Andrzej | last1 =Weroński| first2 = Tadeusz | last2 =Hejwowski | chapter = Creep-Resisting Materials}}</ref>