3175.     SHIMURA, S.  [Study of the Structure of Cementite.]  Proc. Imper. Acad. (Tokyo), vol. 6, 1930, pp. 269-271; Proc. World Eng. Cong., Tokyo, 1929, vol. 34, 1931, pp. 223-225; Chem. Abs., vol. 24, 1930, p. 5271.

        Preliminary report on the X-ray structure of cementite and spiegeleisen, both of which have the same dimensions for the unit cell.  Both belong to the simple orthorhombic lattice V_o and the space group V¹⁶₄.  It is concluded that C is contained as neutral atoms in austenite but comes to take the configuration of the cementite molecule with neighboring Fe atoms as austenite changes to martensite, and it always segregates out as cementite at the A₁ transformation point.  C metastably contained in a-Fe (this is less than 0.03%) also takes the cementitic arrangement.

        SHIRAI, S.  See abs. 1754a, 3178.