The elastic properties, acoustic properties and mechanical properties of the group VB transition metal diborides like VB₂, NbB₂ and TaB₂ have been studied along unique axis at room temperature. The second- and third order elastic constants (SOEC & TOEC) have been calculated for these diborides using Lennard–Jones potential model. The velocities V_L and V_S2 increases with the angle from the unique axis and V_S1 have maximum at 45° with unique axis of the crystal. The inconsistent behaviour of angle dependent velocities is associated to the action of second order elastic constants. Debye average sound velocities of these compounds are increasing with the angle and has maximum at 55° with unique axis at room temperature. Hence when a sound wave travels at 55° with unique axis of these materials, then the average sound velocity is found to be maximum. The mechanical properties of VB₂ are better than TaB₂, because VB₂ has low ultrasonic attenuation comparison than TaB₂. The diborides are good electrical conductors; they are attractive for the same types of applications as other hard refractory materials such as in composite and in hard coating. Traditional applications o such materials are based on their interesting combination of mechanical and transport properties.

elastic properties, VB transition metal diborides, thermal conductivity, acoustic properties