Effects of Al and Si on the twin boundary energy of TiC were investigated by using transmission electron microscopy and first-principles calculations. The results demonstrate that Al was more effective relative to Si to reduce the twin boundary energy of TiC. By electronic structure analysis, the high twin boundary energy of pure TiC could be attributed to the energy penalty accompanying the formation of trigonal prismatic coordination of Ti atoms at twin boundaries. For the Si/Al doped TiC, the lower twin boundary energies were partly due to the absence of the energy penalty accompanying the formation of trigonal prismatic coordination of Si/Al atoms, and were partly due to the stabilizing effect via the formation of π-bonding between C neighbors of Si/Al atoms. The π-bonding between C neighbors of Al was stronger than that of Si, providing an explanation for the larger twin-stabilizing effect of Al.

Effects of Si and Al on Twin Boundary Energy of TiC. R.Yu, L.L.He, H.Q.Ye: Acta Materialia, 2003, 51[9], 2477-84