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Tantalum and its alloys are midway
between tungsten and molybdenum in density and melting points
Tantalum has a melting point of 2996oC and a density of 16.654
gm/cc. Tantalum is one of the refractory metals that offer a
valuable combination of properties. Tantalum can be worked easily at
room temperature. Its thermal conductivity is one-fourth that of
molybdenum and its coefficient of expansion is one-third greater.
Its elevated temperature strength is low compared with Tungsten and
Molybdenum.
Typical Properties
Atomic Number:
73
Atomic Weight:
180.95
Atomic Volume:
10.9
Crystal Structure:
Body-centered cubic, a = 0.33026
Isotope (Natural):
181
Density at 20 oC, g/cc: 16.6, .600 lb/in3
Melting Point:
2,996 oC
Boiling Point:
5,430 oC
Linear Coefficient of Expansion:
6.5 x 10-6 per oC
Thermal Conductivity at 20 oC: 0.130 cal/cm 2/cm/oC/sec
Specific Heat at 20 oC: 0.036 cal/g/oC
Electrical Conductivity :
13% IACS
Electrical Resistivity at 20 oC: 135.0 nΩ ⋅ m
Temperature Coefficient of Electrical Resistivity(0-100 oC): 0.0038 per oC
Tensile Strength:
at
Room Temperature: 35,000-70,000 psi
at
500 oC:
25,000-45,000 psi
at 1000 oC:
13,000-17,000 psi
Young's Modulus of Elasticity:
Room
Temperature: 27 x 106 lb/in2
500 oC:
25 x 106 lb/in2
1000 oC:
22 x 106 lb/in2
Poisson's Ratio:
0.35
Thermionic Work Function:
0.657 aJ (4.10 eV)
Magnetic Susceptibility:
0.93 10-6 cgs
Spectral Emissivity:
.46 (900 oC) (Wave Length Approx. 0.65 micron)
Total Emissivity:
at
1500 oC: .21
at
2000 oC: .26
Working Temperature:
Room temperature
Recrystallization Temperature:
1200 oC - 1400 oC
Stress Relieving Temperature:
850 oC
Thermal Neutron Cross Section:
21.3 b
Polishing: Emery to 000 levigated alumina to
finish.
Etchant: Hf-NH4F Solution. Etch
and Polish repeatedly until grain boundaries appear.
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