3671.     WEVER, F.  [Iron Carbide.]  Mitt. Kaiser Wilhelm-Inst. Eisenforsch. Düsseldorf, vol. 4, 1922, pp. 67-80; Chem. Abs., vol. 18, 1924, p. 1460.

        By X-ray analysis, it is proved that the forms of cementite shown in the Fe-C thermal diagram are not distinguishable by their lattice structure.  Fe₃C crystallizes in a rhombic lattice denoted by the quadratic form sin²θ/2=0.0464x²+0.0367y²+0.0208z².  The edge lengths are a=4.481 Å., b=5.034 Å., c=6.708 Å.  The density is calculated therefrom as 7.82.  Data by the Debye-Scherrer method above 210° show that the magnetic transformation is not associated with a change in the type of lattice.  The quadratic form is expressed by sin²θ/2=0.0456x²+0.0362y²+0.0203z².  The edge lengths are a=4.52 Å., b=5.08 Å., c=6.77 Å.