Enhanced deformability of TiC in Mo-Ti-C ternary system by off-stoichiometry

The deformation behavior of B1-type stoichiometric TiC and off-stoichiometric (Ti 0.96 , Mo 0.04 )C 0.67 was investigated by micropillar compression test utilizing an in situ scanning electron microscope. The yield stress of (Ti 0.96 , Mo 0.04 )C 0.67 was found to be sufficiently lower than that of the stoichiometric TiC. In addition, the {001}<1 1 ¯ 0>, {110}<1 1 ¯ 0>, and {111}<1 1 ¯ 0> slip systems were identified to be active during the plastic deformation of (Ti 0.96 , Mo 0.04 )C 0.67 . The critical resolved shear stresses of these slip systems decreased in the following order: {110}<1 1 ¯ 0> (5.6 GPa), {001}<1 1 ¯ 0> (5.0 GPa), and {111}<1 1 ¯ 0> (4.4 GPa). In contrast to the stoichiometric TiC, which underwent complete fracture at a relatively early stage of deformation, (Ti 0.96 , Mo 0.04 )C 0.67 deformed under >10 % plastic strain without fracturing, with crack preferentially initiating along the {001} plane. The findings demonstrate that the off-stoichiometry of (Ti 0.96 , Mo 0.04 )C 0.67 improves plastic deformability and has a suppressive effect on crack propagation. The enhanced deformability may be attributed to the significantly reduced shear modulus caused by off-stoichiometry.