Titanium is a lustrous transition metal with low density and high strength. It is produced commercially from titanium dioxide via the Kroll process. Titanium has excellent corrosion resistance and high strength at elevated temperatures, making it useful for applications in aerospace, marine, chemical and biomedical industries. It exists in two crystal structures, hexagonal close-packed at lower temperatures and body-centered cubic at higher temperatures, and can be alloyed to modify its properties for different applications.

1. (Ti)
1

2. 
 Titanium is a lustrous transition metal (lllB) with a
silver color, low density and high strength has and
Z=22 and A=48
 Pure titanium melts at 1670oC and has a density of
4.51 g /cm3. It is fairly abundant in nature,
constituting about 1% of Earth’s crust (the 9th
abundant element 0.86%).
 It is highly resistant to corrosion in sea water, aqua
regian and chlorine.
Ti
2

3. 
 Titanium is produced from TiO2 by the Kroll
process.
 The TiO2 is converted to TiCl4 (titanium
tetrachloride, also informally known as tickle), which
is subsequently reduced to titanium metal by
sodium or magnesium.
TiO2+2Cl2+C→TiCl4+CO2
TiCl4+4Na→Ti+4NaCl
Production
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4. 
 The resultant titanium sponge is then consolidated,
alloyed as necessary and processed using vacuum
arc melting.
Con…
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5. 
 The principal ores of titanium are rutile, which is
98% to 99% TiO2, and ilmenite, which is a
combination of FeO and TiO2.
 Rutile is preferred as an ore because of its higher Ti
content.
 In recovery of the metal from its ores, the TiO2 is
converted to titanium tetrachloride (TiCl4) by
reacting the compound with chlorine gas.
Ore
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6. 
 This is followed by a sequence of distillation steps to
remove impurities.
 The highly concentrated TiCl4 is then reduced to
metallic titanium by reaction with magnesium; this is
known as the Kroll process.
 Sodium can also be used as a reducing agent. In
either case, an inert atmosphere must be maintained
to prevent O2, N2,or H2 from contaminating the Ti,
owing to its chemical affinity for these gases.
Con…
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7. 
 The resulting metal is used to cast ingots of titanium
and its alloys.
Con…
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8. 
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Ti ore

9. 
 Ti is stiffer and stronger than aluminum
 Commercially pure titanium has density 4.51g/cm3
 Ti’s coefficient of thermal expansion is relatively low
among metals (Alloy Ti-6Al-4V 8.6*10-6(oc)-1)
 It retains good strength at elevated temperatures
 Pure titanium is reactive which presents problems in
processing, especially in the molten state
Property
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10. 
 Pure titanium has excellent resistance to corrosion
because it forms a thin adherent oxide coating (TiO2)
and is used widely in the chemical industries.
 Titanium alloys are considered biocompatible and
bioactive.
Con…
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11. 
 In the commercially pure state, Ti is used for
corrosion resistant components, such as marine
components and prosthetic implants.
 Titanium alloys are used as high- strength
components in temperatures ranging 25oc -550oc,
especially where its excellent strength to weight ratio
is exploited. E.g aircraft and missile components.
These properties give rise to two principal application
areas for titanium:-
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12. 
 The crystal structure of titanium at ambient
temperature and pressure is close packed hexagonal
(α) with a c/a ratio of 1.587.
Crystal structure
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13. 
 Slip is possible on the pyramidal, prismatic and basal
planes in the close packed directions.
 The coordination number and the atomic packing
factor for the HCP crystal
structure are the same as for FCC: 12 and 0.74,
respectively.
Con…
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14. 
 At about 890oC, the titanium undergoes an allotropic
transformation to a body centered cubic β-phase
which remains stable to the melting temperature.
Alloying of Ti
 All elements within the range 0.85–1.15 of the atomic
radius of titanium alloy substitution alloy and have a
significant solubility in titanium.
 Elements with an atomic radius less than 0.59 that of
Ti occupy interstitial sites.
Con…
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15. 
 The ease with which solutes dissolve in titanium makes it
difficult to design precipitation–hardened alloys.
 Titanium is allotropic, with the HCP crystal structure (α) at low
temperatures and a BCC structure (β) above 882°C.The four
forms of titanium are:-
1. Commercially pure Ti: 99.5% Ti or 99.0% Ti
2. Alpha Ti alloys: 5% Al-2.5% Sn
3. Beta Ti alloys: 13% V-11% Cr-3% Al
4. Alpha-beta Ti alloys: 6% Al-4% V
Alloys
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16. 
 Thus, Al, O, N and Ga are all α–stabilizers. Because
they increase the temperature at which α transforms
to β.
 Mo, V, W and Ta are all β–stabilizers. Since they
lower the transformation temperature, even causing
β to be stable at room temperature.
 Mn, Cr, and Fe produce a eutectoid reaction,
reducing the temperature at which the
transformation occurs and producing a two phase
structure at room temperature.
The alloying elements can be categorized according to
their effect on the stabilities of the α and β phases.
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17.  Molybdenum and vanadium have the largest influence on β stability
and are common alloying elements. Tungsten is rarely added due to its
high density. Cu forms TiCu2 which makes the alloys age hardening
and heat treatable; such alloys are used as sheet materials. It is
typically added in concentrations less than 2.5 wt% in commercial
alloys.
Con…
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18. 
 Hydrogen is the most important interstitial.
 Titanium is capable of absorbing up to 60 at% of
hydrogen, which can also be removed by annealing
in a vacuum which provides a combination of high
ductility, uniform properties, and good strength.
 Hydrogen enters the tetrahedral holes which are
larger in BCC than HCP since BCC Ti has three
octahedral interstices per atom whereas HCP Ti has
one per atom. Thus the solubility of hydrogen is
larger in β.
Interstitials
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19. 
o The niobium is added for oxidation resistance
o The carbon to allow a greater temperature range over which the
alloy is a mixture of α+β, in order to facilitate thermo
mechanical processing.
o This particular alloy is used in the manufacture of aero engine
discs.
Specific–alloys
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20. 
 Al reduces density, stabilizes and strengthens α
while vanadium provides a greater amount of the
more ductile β phase for hot–working.
 One difficulty with the β phase, which has a body
centered cubic crystal structure is, it has a ductile–
brittle transition temperature. The transition
temperature tends to be above room temperature,
with cleavage fracture dominating at ambient
temperatures.
Con…
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21. 
 Titanium can catch fire and cause severe damage in
circumstances where it rubs against other metals at
elevated temperatures.
 This is what limits its application in the harsh
environment of aero engines, to regions where the
temperature does not exceed 400 ◦C.
 But the addition of chromium in concentrations
exceeding 10 wt% helps improve the burn–resistance
of titanium alloys.
Fire
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22. 
Consequences of a titanium fire in an aero engine.
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23. 
 Titanium and its alloys are relatively new
engineering materials that possess an extraordinary
combination of properties. So they have a wide
application in real life.
Some of them are:-
In components which operate at elevated
temperature
In the aerospace industries
Application areas
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24. 
In the petroleum and chemical industries
Car suspension springs
Con…
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25. 
Heat Exchanger materials
Die-cast parts for automobiles, luggage, and
electronic devices
biomedical implants such as hip prostheses
Con…
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26. 
Marine components
Airplane structures and Forgings of maximum
strength for aircraft.
Con…
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27. 
 Titanium and its alloys are similar in strength to moderate-
strength steel but weigh half as much as steel.
 The material exhibits very good resistance to corrosion, has low
thermal conductivity, is nonmagnetic, and has high-
temperature strength.
 Its modulus of elasticity is between those of steel and
aluminum at 16.5 Mpsi (114 GPa).
 Because of its many advantages over steel and aluminum,
applications include: aerospace and military aircraft structures
and components, marine hardware, chemical tanks and
processing equipment, fluid handling systems, and human
internal replacement devices.
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Summary

28. 
 The disadvantages of titanium are:-
Its high cost compared to steel and aluminum and
The difficulty of machining it.
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Drawback

29. 
4 UR PATIENCE.
10Q
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