The effects of Si in TiC were investigated by using high-resolution electron microscopy combined with high spatial resolution analytical electron microscopy. The results demonstrated that Si could reduce the twin boundary energy of TiC; leading to the formation of many 2-dimensional defects in TiC grains containing Si. These defects were identified as being micro-twins which were four (111) spacings thick, and structurally related Ti3SiC2 platelets only one unit-cell thick. The twin-stabilizing effect of Si was explained in terms of the coordination environments of Si. Very thin Ti3SiC2 platelets were formed, accompanied by the segregation of Si atoms and C vacancies to the twin boundaries. Micro-twins and Ti3SiC2 platelets were found to grow in 2 dimensions, with the Si totally confined within the defects.

Si-Induced Twinning of TiC and Formation of Ti3SiC2 Platelets. R.Yu, Q.Zhan, L.L.He, Y.C.Zhou, H.Q.Ye: Acta Materialia, 2002, 50[16], 4127-35