LAUSR

Abstract Excellent elasticity and thermal stability are both essential for the applications of ultra-high temperature sealing materials. Since strain-stiffening behavior guarantees the materials can sustain large strains without initiation of irreversible defects, seeking for strain-stiffening materials with good thermal stability is significant for the development of thermal sealing at ultra-high temperatures. Strain-stiffening behaviors of crystalline Y 2 B 3 C 2 , a new member of ultra-high temperature ceramics, are predicted under (010)[001] and (010)[100] shear deformation. The moduli against these two shears are extremely low at first, but gradually increase to handsome values of 62 and 101 GPa. The ultra-high ideal shear strain and considerable ideal stress indicate the promising applications of Y 2 B 3 C 2 in thermal sealing at ultra-high temperatures. It is noticed that the strain-stiffening effect is originated from the deformable planar B-C network. The special bonding features in the CBC-chain are found to be responsible for the easy distortion of the covalent network.