Anisotropic elastic properties and ideal uniaxial compressive strength of TiB2 from first principles calculations

Key words: 
• ideal compressive strength /
• electronic structure /
• elastic property /
• first principles calculation

Abstract: The structural, anisotropic elastic properties and the ideal compressive and tensile strengths of titanium diboride (TiB2) were investigated using first-principles calculations based on density functional theory. The stress–strain relation-ships of TiB2 under <10(ˉ1)0>, <(ˉ1)2(ˉ1)0>, and <0001> compressive loads were calculated. Our results showed that the ideal uniaxial compressive strengths are|σ<(ˉ1)2(ˉ1)0>|=142.96 GPa,|σ<0001>|=188.75 GPa, and|σ<10(ˉ1)0>|=245.33 GPa, at strains?0.16,?0.32, and?0.24, respectively. The variational trend is just the opposite to that of the ideal tensile strength withσ<10(ˉ1)0>=44.13 GPa, σ<0001>=47.03 GPa, andσ<(ˉ1)2(ˉ1)0>=56.09 GPa, at strains 0.14, 0.28, and 0.22, respectively. Fur-thermore, it was found that TiB2 is much stronger under compression than in tension. The ratios of the ideal compressive to tensile strengths are 5.56, 2.55, and 4.01 for crystallographic directions<10(ˉ1)0>,<(ˉ1)2(ˉ1)0>, and<0001>, respectively. The present results are in excellent agreement with the most recent experimental data and should be helpful to the understanding of the compressive property of TiB2.