Iron

Symbol: Fe
Atomic Number: 26
Atomic Weight: 55.847
Element Classification: Transition Metal
Discovered By: Known to the ancients
Discovery Date: n/a (Unknown)
Name Origin: Anglo-Saxon: iron; symbol from Latin: ferrum (iron).

Density (g/cc): 7.874
Melting Point (K): 1808
Boiling Point (K): 3023
Appearance: Malleable, ductile, silvery-white metal
Atomic Radius (pm): 126
Atomic Volume (cc/mol): 7.1
Covalent Radius (pm): 117
Ionic Radius: 64 (+3e) 74 (+2e)
Specific Heat (@20C J/g mol): 0.443
Fusion Heat (kJ/mol): 13.8
Evaporation Heat (kJ/mol): ~340
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 460.00
Pauling Negativity Number: 1.83
First Ionizing Energy (kJ/mol): 759.1
Oxidation States: 6, 3, 2, 0, -2
Electronic Configuration: [Ar] 3d6 4s2
Lattice Structure: Body-Centered Cubic (BCC)
Lattice Constant (): 2.870
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 4.0
Brinell Hardness [/MN m-2]: 490
Vickers Hardness [/MN m-2]: 608

Note: Iron-based alloys account for a large portion of all metals production. The range of compositions and microstructures of iron-based alloys is far wider than any other system. Pure iron is soft and ductile. Development of scratch-free and deformation-free grain structures is difficult. Sheet steels present the same problem, which can be complicated by protective coatings of zinc, aluminum or Zn-Al mixtures. In general, harder alloys are much easier to prepare. Cast irons may contain graphite, which must be retained in preparation. Inclusions are frequently evaluated and quantified. Volume fractions can vary from nearly 2% in a free machining grade to levels barely detectable in a premium, double vacuum melt alloy. A wide range of inclusion, carbide and nitride phases has been identified in steels. Addition of 12 or more percent chromium dramatically reduces the corrosion rate of steels, producing a wide range of stainless steel alloys. Tool steels cover a wide range of compositions and can attain very high hardnesses. Preparation of ferrous metals and alloys is quite straightforward using the contemporary methods. Edge retention and inclusion retention are excellent, especially if automated equipment is used.

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