Titanium

Symbol: Ti
Atomic Number: 22
Atomic Weight: 47.88
Element Classification: Transition Metal
Discovered By: William Gregor
Discovery Date: 1791 (England)
Name Origin: Greek: titanos (Titans).

Density (g/cc): 4.54
Melting Point (K): 1933
Boiling Point (K): 3560
Appearance: Shiny, dark-gray metal
Atomic Radius (pm): 147
Atomic Volume (cc/mol): 10.6
Covalent Radius (pm): 132
Ionic Radius: 68 (+4e) 94 (+2e)
Specific Heat (@20C J/g mol): 0.523
Fusion Heat (kJ/mol): 18.8
Evaporation Heat (kJ/mol): 422.6
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 380.00
Pauling Negativity Number: 1.54
First Ionizing Energy (kJ/mol): 657.8
Oxidation States: 4, 3
Electronic Configuration: [Ar] 3d2 4s2
Lattice Structure: 1.588
Lattice Constant (): 2.950
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 6.0
Brinell Hardness [/MN m-2]: 716
Vickers Hardness [/MN m-2]: 970

Note: Pure titanium is soft and ductile, but is very easily damaged by twinning in sectioning and grinding. Preparation of commercially pure titanium, which is a popular grade, is very difficult, while preparation of the alloys is somewhat easier. Some authors have stated that titanium alloys should not be mounted in phenolic resins as the alloys can absorb hydrogen from the resin. Further, it is possible that the heat from mounting could cause hydrides to go into solution. This is also possible with castable resins if the exothermic reaction of polymerization generates excessive heat. If the hydride phase content is a subject of interest, then the specimens must be mounted in a castable resin with a very low exotherm (long curing times favor lower heat generation, and vice versa). Titanium is very difficult to section and has low grinding and polishing rates.

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